rearend question

[bmaier]

Setup: '79 1/2 ton, 350/350 combo w/ edelbrock performer intake, edelbrock 600 cfm carb, long tube headers, straight 2.5" exhaust, 4" lift and i run either 33's or 35's.

Question: i know i have a decent setup but i feel like im lackin some power and its a little hard to turn them 35's and the gears in my rearend are uknown and i was wondering if 3:73's would be good or do i need something different.

thanks

[Blazin]

My opinion but 35s need at least 4:10s.

[VileZambonie]

I would say at least 3.73:1 but if you swap in a 700R4 def go with 4.10:1

[SUX2BU99]

I got 26.5" tall tires and 2.76s and it's lame. I was thinking 3.42s or 3.73s. With 35's, for sure 3.73 or higher. That's a tall tire.

Speaking of, will ANY 12 bolt (or even 10 bolt) from 73-87 (91) 1/2 ton rear end directly swap to my truck? It has a 5-lug 12 bolt in it. Just want to know when I'm hunting for used diffs. I'm seeing quite a few 4.10 14 bolts but those are always 8 lugs.

[HAULIN IT]

Sux, Yes they will, you could also get a 12 bolt 4x4 rear (easier to find the 3.73-4.11) & put your shafts in it to get rid of the 6 bolt wheels. Lorne

[bmaier]

okay, thanks guys. i was thinkin either 373's or 410's and since i plan on swappin in a 700r4/205 combo i think i will go with 410s. thanks again guys.

[static22]

On this same subject has anyone set up a posi rear end. I need a posi and have considered this or a spool. It doesn't get driven much and I've had guys tell me the spool should work since the rear is lighter than most cars. It makes me nervous I may twist the axle in half if I make a tight turn.

[comp]

On this same subject has anyone set up a posi rear end. I need a posi and have considered this or a spool. It doesn't get driven much and I've had guys tell me the spool should work since the rear is lighter than most cars. It makes me nervous I may twist the axle in half if I make a tight turn.

is is easy to do with stock axles

[78 Chevyrado]

For driving on pavement of any kind, get a locker, posi, etc.  For DIRT, etc ONLY get a spool.  or 35's I'd get a 4.10 or higher (numerically.) I'd also like to have at least a 12 bolt rear end.  I'm wary of 10 bolts since my 87 with 80k miles and a 10 bolt  broke both spider gears and ruined the tranny in the process, pulling a 1500lb trailer while taking off easy.

[static22]

OK, no spool. If the 10 bolt broke I would say go with the 12 bolt if it makes you feel more comfortable. Are you looking for a used one or one to build?

[SUX2BU99]

Thanks for the info Lorne. I did a search on here and saw that 10 bolts and 12 bolts have different yokes on them. Did the vans from the same period get the same diffs? Meaning, 12 bolts up to 81 and then 10 bolts for 82-up?