rear end

[str8bloc]

i have an 83 lwb basic truck came 305 th350 just wanna know the rear gears the diif plate is gone no ac r they 2.73?

[eventhorizon66]

This gets asked alot here.  And unless you are the original owner and you have the RPO sticker (inside glovebox), there is only one way to be sure.  Pop the diff cover off (it's probably time to change the oil anyways), count the teeth on ring and pinion gears, and divide # of ring teeth by # of pinion teeth.

[Irish_Alley]

i thought you use the number thats on the ring / by the teeth on the ring?
but anyway this should also help if you have a tach if not then popping your cover or looking for a tag is your only option but like even said you probably need to change that oil anyway

the formula for rear ratio is
if your running 50 mph @ 2k w/ 38" then
your ratio would be about 4.53
rpms x tire size / 336 / mph = ratio
2000 x   38    / 336 /  50    = 4.53

or you could use this web site
http://www.idavette.net/tech/ratioc.htm
found them after this whole ideal about the formula

[kiowamec]

Pull the cover and spray it out with a couple cans of carb/brake cleaner.
If its posi add some posi lube when you refill.
Check numbers on the ring gear for the ratio.
http://www.buickperformance.com/posi.htm

[eventhorizon66]

i thought you use the number thats on the ring / by the teeth on the ring?

Pull the cover and spray it out with a couple cans of carb/brake cleaner.
If its posi add some posi lube when you refill.
Check numbers on the ring gear for the ratio.
http://www.buickperformance.com/posi.htm

I guess you could just look for a number, but that would spoil the fun of counting.

[Irish_Alley]

counting the ring thats not hard but its counting the pinion that would be fun

[str8bloc]

the rpo codes r E63,GQ1,G50,LE9,MX1,N41,XJU, ZY1,Z53,59L,61W GQ1 is standard what is the standard gear ??

[Donut]

Put a chalk mark on the drive shaft and a tire, jack up the rear, rotate a tire (by hand) and count the number of tire rotations to turn the drive shaft 1 revolution. (safely of course) ie, 2-3/4 tire rotations to 1 drive shaft= 2.73  (at least I hope I didn't get it backwards

Some RPO code lookups-http://www.nastyz28.com/gm-rpo-codes/

[eventhorizon66]

2-3/4 tire rotations to 1 drive shaft= 2.73  (at least I hope I didn't get it backwards

You did get it backwards.  What you described was a 0.36:1 final drive, LOL.

[Donut]

Figures, .  I know what I was thinking, but due to multiple interruptions, my thoughts got scrambled.

I did this last summer with my truck (the correct way) to verify that in it's 35 year history the gear ratios were still correct.  Who knows what been swapped and why.

Try this link-http://www.jedi.com/obiwan/jeep/misc/gearratio.html

[str8bloc]

well i pulled the cover to change the oil and the stamping reads 2 gm1235126 13 40 8 82 is this 3.08?

[zieg85]

40/13=3.08

[str8bloc]

r these ne good?

[zieg85]

r these ne good?

Personally I have always liked the 3.08.  It is a good all around gear, decent on the highway and in the city.  My $.02