T-56 for 4WD or am i dreaming??

[mickman77]

Hey all, new here and have a question. My '77 K-20 project is under way. Yanked the 400 sbc and dropped in a 454 for some muscle. would love to figure out a way to mate a T-56 6 speed and an NP205. Is this a possibility or am i just hoping for some dilusional (and crazy expensive) fantasy?
At the moment the original th350 and np203 are still in the truck. Rolling down the interstate here in montana on 33's with 4.10 gearing has the mighty motor spinning faster than i care for. Have entertained the idea of putting either 3.73's or 3.56 in the axles but i think a beefier tranny should be the first order of business. whadya think?? any advice would be greatly appreciated.

[Jonboy]

I would think 4.10's would be almost ideal with 33's. I think you might be better served to have a 700R4 built for the truck, and get an adapter for the 205.

[Pyrotechnic]

With a divorced transfer case it's very possible. You may find the 0.50 6th gear a bit useless unless you gear your axles for it. I recall the stock torque handling of the LT1 T56 to be around 450 lb/ft so your best bet would be to find one that's been rebuild and gone through to handle more power.

2.66 1.78 1.30 1.00 0.74 0.50

Another good one is the ZF S6-650 6 speed found behind the newer Vortec 8100 and Duramax. The torque rating is 650 lb/ft. Whats nice is that the middle 4 ratios are a lot like a car 4 speed, but you've got the granny gear and overdrive gear.

5.79 3.31 2.10 1.31 1.00 0.72 5.23

[Captkaos]

For a 4x4, I would rather have the NV4500..

[willett]

i run 3.73 with an np205, 454 and a turbo 400 and i'm about 3000 at 60mph

oh.. on 35's

[K30cummins]

if your set on the t56 and not worried about the torqe issue might have to use a divorced 205... im running one in my cummins swap in my k30

[mickman77]

not sure how to set up a divorced t-case. a u-joint between out-input yokes? wouldn't that require a 2nd crossmember?