do they make those over/under drive units for manuals?
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(we jacked your thread so here's the link to the gearvendor....check it out!  mudb8)
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http://www.gearvendors.com/cg2wdt.html


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There are a few but it is FAR wiser, easier and cheaper to swap tranny out for a modern one with OD. Given the selection of OD trannies out there, there is little need for bolt on OD units as there days are numbered. 20 years ago there was not many good OD trannies out there but such is not the case today.  

well i wanted to post on manual or auto but for some reason i couldn't. the sm 465 has a lower 1st and reverse gear so i thought if i could add an aftermarket od then that may make my life with my 4 speed a lil better. if it costs more then the swap then i'm not interested. btw between the nv4500 and zfs6 i think i like the nv4500 better. it has a lower 1st and reverse then the zfs6. what are the torque ratings for these?  

Both are rated BB torque and ZF6 is Dmax rated too. Both are more tranny then you will likely ever need capacity wise. I would stop fixating on the SM465. It was a good box in its day as I owned a few 465 long long ago and even a few SM420's too even longer ago. Today OD trannies with deep axle gears blow those old trannies away.  

check this out, It will make your m465 into a 7 speed, so you want a 5 spd for....? it's .78to1, I have one in my 86 dually.......th400-205, awesome my uncl has one in his 440 powered motorcoach and a buddy of my oldman's has one in a 83 with a 4spd nearly splits the gears. o, and good luck breaking it.LOL


http://www.gearvendors.com/4x4.html  

Still cheaper and better to upgrade tranny. BTW, a 4L80 is nothing more than a THM400 with OD added and a electronic valve body too. What ever you can do with a THM 400 you can do better with a 4L80 and run a even deeper axle ratio too and still cruise at a lower RPM plus not THM400 every had a locking converter either and a $3/gallon is not a good choice as lack of it is good for a 5 to 7% or better MPG loss in a HD truck. The 400 was a good tranny in its hey day like 465 but those days are gone along with $1/gal or less gas too.  

this is no elctronics besides a switch for the shifting and a .78 to 1 ratio, they really don't cost more than a 5spd swap or the headace of messing with a 4l80, this is something worth doing some reading on as it works with old and more desireable trannies. thats why I didn't put the 4l80 in my dually that came with the 6.5 diesel I bought from a wrecked 96 from insurance auto auctions plus I still have the 205 t-case with 3.8 ratio insalled in it. I do fully agree on the 5spd and 4l80 being good choices, this has more options and more gears  

The 4L80 is electronically controlled. It is not like 700R4 and THM350 which had a throttle valve cable on them nor THM 400 which had a vacuum modulator. Also, the 4L80 has a .75 OD and the 700R4/4L60 has a .70 (actually .696 but .7 is close enough) Because the 700R4 needs no computer to function it makes a nice upgrade to a old 3 speed auto truck/4x4.  

that right I'm a 700 fan also, just not for a tow rig, that's what makes the non electic th400 and gearvendor a healthy unit,

I wonder what the rpm difference is in the .78 vs the .75 of the 4l80?

I don't know the ratios, the 400 has straight cut planitaries available in the HD box vans and some huge motorcoaches for a lower 1st and 2nd.

I tow with the 98 suburban alot, (24,500 combined weight)4:10's and 265x75-16 toyos, It starts off the line easier though I'm starting to get a little chattering in OD, I've yet to burn up a 400 in the dually with the vendor and it does less shifting, in fact it is still the original, the old man did put a transgo -2 shift kit in it way back when, dad bought the truck new then I got it when he bought his 93 5spd, now he's tired of shifting that.  

GM never offered THM400 with any other gear ratios in its life span. For a while there was a after market source that offered a 2.74  and 1.58 first and second as I recall. The 4L80 uses THM400 gears and parts in main unit but the electronic control cannot deal with different gear ratios so I never heard of it being applied. GM did offer some dual stator torque converters in some HD apps on THM 400's and still on some 4L80 apps too. (dual stator raises stall ratio to about 3 to 1 or a bit better vs about 2 to 1 of standard converter) Nothing wrong with towing with a 700R4 if you have proper axle ratio behind them. Also, it is not a tranny to tow in OD with unless you have a really deep axle ratio relative to tire size because it is pretty tall.  

there was a lower planitary set for a th400, I have two sets of them, one came from a box van and the other came from a burnt motorcoach I bought for parts. maybe they are the same as the aftemarket or they are aftermarket, I do know they are hard to find and spendy, just don't know what the ratio's are, when I freshen up the dually I'm going to put them in it. I'll have to do some looking I guess, the passenger planetaries are angle cut, the truck HD are straight cut. I won't tow anything heavy like my toy hauler with a 700 at all in OD, and I refuse to drive 50mph from the high rpm. so for me in that type of situation the 700 is out of the question, It would be rediculous to put a vendor on a 700, wow, maybe not LOL...I did think the 4l80 had a lower 1st, huh, guess not according to the chart I just saw.

there are different aftermarket low gear options for the th350 also  

I am not sure where you get this high RPM tow thing. Sounds like you run a OTR rig but gas P/U's like RPM when towing unlike OTRs and oil burner P/U's. I have drive cross country at 3000 RPM give or take with SB's many times and no problems at all. For some strange reason though some are hung up on lugging them and then wonder why towing power is poor or tranny fries. I have a 32 foot unclosed cargo trailer with a HD frame and twin 7K dexter axles. It weighs just under 3 tons empty and have a 15K GVW rating (it is a serious pull type trailer) When i9 went to get it my K3500 was down with brake problems so I had to use my 89 1500 4x4 burb that I bought new and has over 180K on it now. It did not even really break a sweat with it and pulled it well with its stock type "C" tires and stock factory tow package. I did not even think twice about it. ALso, once this summer I had to retrieve a trailer loaded with big mowers for a friend (tow vehicle died) that weighed close to 5K and towed it it with ease for 110 miles and even used OD a good bit too as it pulled it well. (you would not believe the MPG I got doing it either) Been towing for well over 35 years now so I know what can do what. I even logged a few hours in some tractor trailers long ago as well as some serious dump trucks too with heavy trailer too. I let my chaufers license lapse many years ago.  

yep, with the sbc gasser I agree, my tow rigs are 6.5 turbo diesels. thats where I get off about the high rpm. we frequently go from portland to san bernardino,ca to the mx races at glen helen and glamis. shorter tirps are over some steep 8+ percent grades around 200 miles to florence, or. and bend, or. during the regular season it runs to woodland and vancouver, wa. almost weekly.

I do drive OTR so diesel is a large part of my life, and I grew up in and around diesels.  

ok so what i'm interested in knowing is do they make an overdrive unit for my sm465/np205, and does this give me the "effect" of having an overdrive tranny?  

The 6.5 is a prechamber engine and it is very RPM friendly for a diesel. That engine will safely rev more than you think. This may sound funny but of all the diesels GM has put in P/U's, the 6.5 turbo was my favorite and the only one I would have owned. I drove many of them over the years and thought they were funny to drive.. Back in 95 I was out  in Helena MT test driving trucks  and taking them north of town on a long steep climb on highway to see what "beans" they had (dealers did not mind either) and the GM 6.5 could take it at near 80 MPH at hill crest, CTD was second in mid to upper 60's and PS could not even make 60 then. Granted things have changed a lot since then but back then that 6.5 liked to wind up and eat that hill up (it was a 5 speed too) It kinda drove more like a big noisy gas motor than a diesel. When I got my 2000 K3500 new, if they had had a 6.5, I might have tried it as then it was only a 1800 dollar option too.