Hi guys i just bought a 87 D150 pickup yesterday, and i've been going through and looking up the major compnents, engine, transmission and the rear, i already know my truck is quite a different truck then usual, i have a 400 B motor in mine guy that owned it before me swapped everything in. My question is i'm use to the tags on the rearends to decode it, ratio, etc. I know w/ the 12 bolt cover its going to be a 9 1/2, trucks a 2wd...i'm trying to figure out what the ring and pinion ratio and is, and the old owner chept saying it was posi...pretty sure in mopar world its sure grip right? lol anyway on the front side of the rearend in various places saw many different numbers. can any of you guys lead me in the right direction. thanks

 

Sure Grip if it's a Mopar setup, but someone could have put many different brand posi units in there.

Besides opening it up I really have no SURE way of knowing what's in there.

 

The Mopar axles are 7 1/4, 8 3/8, 9 1/4. The 9 1/4 has 12 bolts. Posi/sure grip, different names for basically the same thing. Jack both rear wheels off the ground and turn one tire. If the other tire turns in the same direction it is posi/sure grip and needs an additive to the fluid when changed. Another way to ID a sure grip is to look inside the filler plug. When you look into the "windows" of a sure grip differential you will see springs.

Let one tire down. Mark the bottom of the raised tire with chalk. Also mark the drive shaft with chalk. Turn the tire 1 revolution while counting the revolutions of the drive shaft. example: A 4.10 ratio will be shown by the drive shaft revolving 4.1 times a 3.55 will rotate the drive shaft 3.55 revolutions. This is crude but effective due to a limited number of ratios available, just pick the closest one.

 

thanks guys, i will get into that today, appreciate the responses, i'll probably just pull the cover and see what i have going on.