rearend question

[burkitk]

i am wanting to swap my 9 1/2 rearend with a corp. 14 in my 87 k 20.  What year of rearends will fit?

[zieg85]

Pretty much everything from 73-87 on up to 1991 Suburban with a 454.  Just keep in mind all the gear ratios available for the semi-float may not be available for the full float.  My $.02

[burkitk]

So I might have to switch out my front end as well?

[zieg85]

What gear do you have?  If you don't know look on the list of RPO codes on the sticker in the glove box and with some checking I can tell you.

[burkitk]

I'm not positive this is the stock rearend this truck had some work done to it before I owned it.  I guess I will have to pull the dif cover and count teeth.?? 

[zieg85]

I checked and it seems if you have the common 3.73 or 4.10 gears out back the Full Float comes in those ratios.   http://www.pirate4x4.com/tech/billavista/14b_bible/index.html  is a good reference on the rear ends.

[Captkaos]

You don't have to count teeth if you pull the diff cover, just find the 2 numbers stamped on the ring gear and divide. 

The front ratio must match the rear.

[muddpuppy01]

dont even have to open up the rearend to find out.

jack one side up and mark the pinion location to the housing and mark the tire on the side you have up and turn the tire two full turns and count the amount of times the pinion turns.

if its goes just over 4 turns on the pinion 4.10 if it dont make it 3 3/4 turns you got 3.73

[Captkaos]

Why not open it up.  I am sure it has NEVER had the fluild changed and if it has, you don't know how long ago it was.