I would like to know how complicated it would be to swap out my V-6 Vortec with a small V-8 (305 or 350)and would it really be worth the trouble. I've heard the 4.3 has the same block as the 350 just minus two cylinders. But would I have to change the computer and wiring harness too. My 4.3 has 180,000 miles on it so it's time to do something.  

it's not a compicated swap at all. i would go with a 350 over a 305. you should be able to find a good donor at a junk yard with the v8 harness, computer and all relatively cheap. they are a dime a dozen! but i would think about this...a good friend of mine has a 93 Z71 with a 4.3/5spd that he bought new. he ran it for over 200k miles on just slightly bigger tires. when it finally started smokin' he replaced it with a reman'ed 4.3 and stepped up to deeper gears and still pulls his dirt track car, hay, and cows and never once said he shoulda had a V8  

Well I have to say that my 4.3 hasn't given me a lick of trouble either. I'm running 32" tires but want to upgrade possible to 35" but if I can get away with just gears I will. I was thinking of 4:10  

USAFchevy:
Well I have to say that my 4.3 hasn't given me a lick of trouble either. I'm running 32" tires but want to upgrade possible to 35" but if I can get away with just gears I will. I was thinking of 4:10

Try thinking about 4.88 at very least. It would be a a bit of a slug with 4.10's and 35's. So many are hung up on 4.10 is seems. It is a great gear with 29's or 30's and OD but not 35's.  

Do you think the 4.3 will be able to pull the 35" tires and a 6" lift with just gears?  I was told that might be a little too big a tire for a V-6 to handle.  

the 4.3 wil do well with 4.88's or 5.13's

the sbc is a direct bolt in swap.  

USAFchevy:
Do you think the 4.3 will be able to pull the 35" tires and a 6" lift with just gears?  I was told that might be a little too big a tire for a V-6 to handle.

Yes it will do a fine job with at least 4.88 gears in it and it will surprise you. Many blame engine for lack of power with big tires when the real problem is lack of proper axle gears.  

thats kinda like my 4500# rubi, 5.13's with 34" rubber,
now it scoots... the truck is only another 1000#  

If his truck is a manual I would try 4.88's but if it is a automatic I would go with 5.13's because 4L60 has a pretty tall OD and even a 5.13 will be a tame in OD with those tires.  

yep, I'm with ya there, you wouldn't belive the crap I took when I was after 5.38's. ended up with 5.13's for 34's cause I don't want to swap out my factory d44 rubicon locker 5.38's aren't avaliable for it. my od ratio is almost the same .69 in the 42rle jeep and .6999 in the 4L60 gm automatic.  

so basically I should keep my engine and rebuild it when necessary, shove some 5.13's in front and rear and slap on my 35" tires and I'll be good to go. I'm not too familiar with gears and 4X4 stuff I'm a bit of a newbie to this. I doubt I can even put the lift on.  

what tranny do ya have?

and ya should figure ot what your future plans are gonna be to make a good decision. the v-8 can handle a slightly higher ratio like a 4.88.

anyhow, yer buddy with the same v-8 powered truck, stock gears, and 35's 'll get whooped by yer little  v-6 with 5.13's..  

USAFchevy:
so basically I should keep my engine and rebuild it when necessary, shove some 5.13's in front and rear and slap on my 35" tires and I'll be good to go. I'm not too familiar with gears and 4X4 stuff I'm a bit of a newbie to this. I doubt I can even put the lift on.

Yep, you would be good to go and the 4.3 with 5.13's and 35's it will do a fine job and will surprise your buddies with V8's and stock gearing. Sounds like you will have to farm out gear change. What you want to do is get gears on line and then shop around for best deal getting them installed. BTW, if axles are running quiet not there is no need to go the expense of new bearing in diff and that can save you a few hundred too. Being that this a a 4.3 truck I am sure axles are likely in fine shape internally.  

I have the 4L60 EI. And i'm leaning more towards keeping my 4.3 and putting in the gears.  Sounds like the cheaper route.  And since my engine hasn't shown any signs of trouble why change it.  Would it hurt to put the gears in with just my 32" tires until I get the lift and 35's  

USAFchevy:
I have the 4L60 EI. And i'm leaning more towards keeping my 4.3 and putting in the gears.  Sounds like the cheaper route.  And since my engine hasn't shown any signs of trouble why change it.  Would it hurt to put the gears in with just my 32" tires until I get the lift and 35's

It will not hurt at all. With 5.13's (which I think would be a better combo vs 4.88 the more I think about it) you would only turn a little over 2400 at 65 MPH in OD with 32's. With 35's it will be turning about 2200. If you gear it much taller it will not pull OD well with 35's. As side benefit of this that you will also see a improvement is traction on and off road due to less chassis twist and axle wrapup for drive shaft counter torque. You will be quite pleased with results and not think again of a engine transplant. The 4.3 is a good engine as it is a 350 minus two cylinders and with good maintenance can have a very long service life. BTW, you can also perk it up some by resetting base line timing to about 8 BTDC (TBI motors will let you do this)and using 89 octane or better fuel in it. You will feel a difference in the way it responds and MPG will increase some too.