Axle Swap

[taylorbg]

I came across a 1991 3/4 ton 4x4 Suburban with 4:56 gears. I have a 1972 4x4 Suburban 350/350 with 33 inch tires. The main purpose of my Burb is to tow my boat, which right now is struggling, especially on any hill.

My question is, if I wanted those gears will the 91 axles swap in? Are those gears too low for 33 inch tires, or should I be looking for closer to 4.10? It also has a 4180 trans. Would that be better for towing than the current 350?

[04sshd]

3.73 or 4.10 would be ideal for 33" tires. 3.73 is a good gear ratio for the 350 trans, if you go 4.10 you will have your towing range but your RPM's will be high on the highway.

If you want to do an axle swap, you might have to re-weld the axle mounts. Aside from that they should go right in. 91 is still solid front axle on the burbs so at least you won't have to mess with the IFS on the newer bodies.

[vectorit]

I currently run 4.57 gear ratio, which is the original ratio for my Suburban.
They are very low, and I run 33" tall tires.
Highway speed is 65, any faster I go into secondaries.

[Cobalt964ruf]

in my 2001 k2500hd I have oem 4.10's with a 4l80e and run 35's. it pulls very well still, and highway 75mph is 2300rpm's with the overdrive trans. best of all worlds.

post script; now grant it my 2001 does have a 400hp lsx tho too. so pulling really isn't an issue.

[taylorbg]

I found a metal tab on one of the bolts on the front axle. It says 373, so I guess at this point I can assume the gears are 3.73? Assuming no one has re geared in the past. These should work in the short term, maybe at a later date go to a 4.10 if I feel the need. Maybe I will look at other things to change so it is not a major dog pulling that boat, especially up the smallest hill.