88 to 98 Chevy truck 10 bolt 3.42 rearend 6 lug

[pvienneau]

Hello all, I just found a 88 to 98 4x4 rear end 10 bolt 6 lug from a Chevy truck. I want to put it behind a T4 55 6 cylinder 235. Should get me to 70 75 MPH on Hiway.

What do you think? Anyone have this set up in there 49 3100?

[robertsjm711]

What is the gear ratios for the T4? Is it the one with the granny gear? Either way if it is a 4 speed 4th gear will be 1:1, so you need to look at rpm's. I use Randy's Ring & Pinion RPM calculator (transmission ration rpm box). The goal is to get to a good rpm of your engine, and with a 3.43, 26" tires (I guessed) and 70 mph you are at 3324 rpm. That seems a little high for sustained highway driving, but I am not super familiar with 235's.

I have a Muncie M20 4 Speed (same 1:1 4th gear) w/26: tires and I am going with a 3.42 (12 bolt passenger) also, but my highway speeds here in Oregon are 55-65 so I will be @ 2873 rpm, which is good for my 5.3l.

Also look at width, my 12 bolt was wider than the stock so I had to get offset rims to get it to fit. Again my setup is a little different, I wanted to stuff some 225/60/16s under the fenders.

Also2.0, you might look at the 1st gear combination (final drive?) - mine is a 2.56 1st, so multiple 2.56*3.42 (rear end ratio) = 8.755. If I remember correctly 7 to 8 is good daily driving get-up-n-go, ~10 is drag racing and less that 6 to 7 is weak take off (but good highway w/o overdrive trans).

I know this may be a little more than you asked but I recently went through this and wish I didn't pass up a R&P set w/ carrier to replace my stock 2.29s. (yuck)

https://www.ringpinion.com/calculators/Calc_RPM.aspx

[pvienneau]

It is the SM420 7.05:1 Ratio

[mongocanfly]

agree with robert...pull a tape on the wms2wms width..its going to be wide..

[robertsjm711]

With that low of 1st it is basically a 3 speed with a low, I have heard these trans will technically/physically work but are not as fun to drive. I had one in an old Chevy pickup, great for towing but not much else.

Are you going for heavy towing or 4x4?

Worst case you can put it in first, jump out and pee on a tree, and jump back in.

Just my 2 cents. (or 3 by now?)

[pvienneau]

Not 4X4. A truck with better than the 4.10 in it now.