So, I was just curious on a scale of 1 to 10 how feasible this would be.

'87 K5 Blazer, with a 5.9 Cummins Turbodiesel and Ford 9" axles front and rear.

That's the gist of it, so what do ya'll think?

Thanks.  

This isn't that crazy of a build, its actually a pretty cool one that i would really like to see, lots of people have swapped in 5.9 cummins in the older chevys and the 9 inc axles would be easy but i would suggest for the rear a 14 bolt 10.5 full floater to handle all the power of turbodiesel. if you go to the dieselpower magazine web page you will see 2 ford broncos that have ford 7.3 and 6.0 turbo diesels swapped in and they look really cool but since im a chevy guy i would really like to see a blazer with a cummins!    

I think heavy and your blazer frame up front will hate you  

I think it would be a bad combo. A 1200 lb motor in a lighter frame and short wheelbase would handle badly and be very front heavy and sink like a anchor in soft ground. Weight is not a asset off road but some seem to think that is does not matter when it really does.  

Does anybody remember the military K-5s, they had diesel engines. So it should work, unless the Cummins is just that much heavier than the ones that came in the Milspec K5.  

THe Military diesel version had a motor that weighted about 450 lbs less. Those engine were designed for a lighter weight vehicle.(plus it had a MUCH wider usable RPM range than CTD too) The CTD was designed for a 6 ton plus (empty weight)truck and transplanted into a LD P/U. A 1200 b motor is okay in a truck that can gross 20K and more but not in one that grosses well under 1/2 that. Plus this whole torque thing is over rated, 600 ft lbs at 1600 RPM is the same HP as 300 ft lbs at 3200 RPM. If you use a gas motor and gear it properly it will run circles around a heavy oil burner off road. Many never connect these dots though and never regear and think engine is only solution.  

snoman just doesn't like diesel swaps... i've got a 77 jeep cherokee with the 5.9 liter cummins in it... and i love it... especially offroad... i don't have to keep it revved to keep it moving... first gear and 4 low and it'll idle anywhere i could ever want it to go... plus i get better then 20 mpg... but i definately wouldn't keep the 9" go with a dana 60 or 14 bolt or better... and since they really didn't change the frames on those much between the blazer and the 3/4 ton trucks you might just need to swap in some heavier front springs to handle the weight and then put in a traction bar in the rear... you'll probably want to find a nearly complete donor truck for the swap... and just use the cummins engine mounts and what not...  and i'd suggest a 92 or newer 12 valve cummins... less wiring...  

No, snoman just does not like 1200 pound motors is SUV's. The physics of it is silly. I have had gas power manual tranny 4x4's over the years that I did not have to keep rev'd up or slip clutch to move but then I never believed in lifts and big tires without proper axle gears either. All the extra weight is not a asset off road especially in soft ground. Now if they made a oil burner that weighed about the same as a gas motor and had a truly useful RPM range of more than 1500 RPM or so then I would look differently at it.  

Yeah some of the points sno is bringing up do have thier truth to them but what are your plans for the blazer? how big of tires are you goint to be running? i think before you swap in the motor you should either box the front section of the frame or box the entire frame to help with all the exta wight and tourque of new motor, then you will need springs rated for the extra wight but with a buld this cool why stick to leaf springs? swap in a 4 link coil over system from a dogde 4wd truck that way you won't have such a rough ride if you tune it properly and what trannny are you thinking of running?  

For both space and weight savings, you could consider a 3.9L Cummins 4BT. You can find them easily in commercial step vans like frito lay and wonder bread trucks. Same bore and stroke as the 5.9, just 2 cylinders missing. They weigh about the same as a big-block chevy and while their stock power numbers aren't impressive on paper (most are rated around 105hp and 325 lb-ft of torque)They seem to move those 10,000 lb delivery trucks around just fine, and they can be modified just like the 12-valve 5.9L engines. An added bonus is it doesn't seem to matter what you swap them into, they get at least 20 mpg. Check out this forum http://www.4btswaps.com/forum/index.php. All these guys do is play with the 4-BT engines. Very informative site.

As far as axles go, I'm thinking the Ford 9" may be a little light in a fullsize truck. Sure you can upgrade one with high-zoot carriers, 1/2 inch wall axle tubes and 40-spline shafts, but it will cost a fortune. Theres a reason Dodge put Dana 60 fronts and Dana 80 rears (9 1/4" high-pinion front - 11.5" rear AAM axles 2003+) in their Cummins diesel trucks.

Heck, a few years ago during Top Truck Challenge, A guy running a back-halved 2500 Ram and stock 5.9L Cummins managed to snap an axle shaft on his rear 2 1/2-ton Rockwell!!!