1990 454ss rearend compatibility

[ds454ss]

I have a 1990 454ss it has a 14 bolt rearend and was told 373 gears but it does not have positraction it is 5 lug. I would like it to have positraction. My thinking i would take the internals out of another rearend and put it in mine to get 373 gears with positraction. While looking at different rear ends I have come across a 88 3/4 ton truck rearend. It has 373 and posi and is a 14 bolt rearend but it has 8 lug axles. Would i be able to take the gears out of this rearend and put it in mine? also would like to know what other rear ends would be compatible does it have to be 2wd?

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[sewlow]

Check the axle spline count. IIRC, the housings are the same, just with longer tubes/axles on the 3/4 diff. Along with the amount of wheel studs, of course.
Seems to me that the SS diff used a Gov-Loc carrier. Much better than the 10B version, but in my mind, same crap. Go with a Yukon or Eaton LSD carrier.
Ever set up a rear diff? If not, best left to someone with the right tools, the knowledge & (most important!) the experience.

 

[454cid]

8-lug is probably a fullfloater, or were there semi-floating 8-lugs?

I would look to see what's available in a lunchbox configuration for the existing carrier... most people don't want to deal with gear lash themselves.

 

[PlayingWithTBI]

Here's a thread I started about a 10 bolt lunch box locker, yours will be different but there's a lot of good input as to what options you have.

https://www.gmt400.com/threads/lunch-box-locker-for-my-10-bolt-rear-end.46383/

 

[Donald Mitchell]

Lookup the codes on the tag in your glovebox, see if it lists a G80 or G81 or G86 which is the code for positraction/ Limited slip. I would be surprised to find an ss454 without it. Also cde will tell you the ratio. Everything I have read said the 1990 had 3:73 posi and 91 and later with the 4speed auto had 4:10.

 

[letitsnow]

8-lug is probably a fullfloater, or were there semi-floating 8-lugs?

My truck has a 14 bolt, 8 lug semi float.

 

[Supercharged111]

Check the axle spline count. IIRC, the housings are the same, just with longer tubes/axles on the 3/4 diff. Along with the amount of wheel studs, of course.
Seems to me that the SS diff used a Gov-Loc carrier. Much better than the 10B version, but in my mind, same crap. Go with a Yukon or Eaton LSD carrier.
Ever set up a rear diff? If not, best left to someone with the right tools, the knowledge & (most important!) the experience.

Are you sure about the tube lengths? It'd make sense, those 8 lug drums were pretty damn big. Too bad you can't just slap the 5 lug axles and brakes onto an 8 lug housing.

For clarification, the 14 BSF had a 9.5" ring gear and the 14 BFF had a 10.5" ring gear.

 

[jerry mize]

You can order a Richmond locker assembly for these trucks for around 200.00 bucks there strong and work awsome

 

[1989GMCSIERRA]

I installed a Auburn LS in my truck. 20 years later it still works great. If you’re gonna go through all that trouble I wouldn’t bother with used parts.

 

[Donald Mitchell]

Yours probably needs a clutch pack.