What rear end do I have?
 

Good day to you all! I have recently put 38's on my K5, and am looking into putting in 4.56 gears...however...there are different choices as to what to buy. What size ring gear do I have? I have an 89 K5 with the stock rear end. I believe the GM 10 bolt in that year had the 8.5 inch ring gear? Any info you guys can give me would be awesome!

If you have 38's and want to reliably run them, toss the 10-bolt axles in the scrap pile and put in a D60/14BFF combo. 38's will majorly stress a 10-bolt. That is unless you just want to pound the pavement with it...

Ha ha...yes, pounding pavement is gonna be the majority of my driving unfortunately...I know I know...its probably 80% road, 20% off-road. Plus I just dropped a large amount of cash on tires, wife would kill me lol. How much we talking for the new d60/14bff? New ring and pinion will run me around 300-400 for front and back...do you happen to know what size the 10 bolt is?

Do you rely on this truck for transportation or is it a toy? If it's a toy and you have something else more reliable to fall back on, then stick with the 10-bolt axles until they break.

A D60/14BFF combo could cost as much as $2000 all said and done, but that depends on where you get the axles from and how much you pay initially. You would also need new rims as this setup will be an 8-lug hub.

Your axles should be GM Corporate 10-bolt (8.5-in. 1.28 Axle Dia. 30 Spline) both front and rear. You should verify this though as things could have been changed in the 21 years since the truck rolled off the dealer lot.

It is mainly used for transportation...I go to work and maybe the store a few times a week, wife has a...sigh...Prius. So whenever we go out as a family, we use that. The plan is to get these gears, if the axles break, they break. That'll give me the excuse to upgrade. Thanks for the info...what truck can I find the upgraded rear/front d60/14bff in? Junkyard?

The D60 and 14BFF can be found under pretty much all GM 1-ton trucks (K30's etc) of the same body style as your truck. The 14BFF is also found in the back of the GM 3/4-ton (K20's etc) trucks with the only difference between the 1-ton & 3/4-ton rear axles being the spring perches. A 3/4-ton 14BFF will bolt into any 1/2-ton application where the 1-ton 14BFF will have to have the spring perches moved in.

Seeing how it is a 89 with a 700r4 I would just skip the 4.56's and go to 4.88's or 5.13's. You said 3 to 400 for the ring and pinions, don't forget install kits, and labor unless you are doing it yourself. If you never did gears before then your best bet is to take it to somebody that has the tools and knows what they are doing. A typical gear swap all said and done is around $1000.

Buts that the most fun part, learning to do things you've never done on a truck before.

i got lucky and found a complete 82 k30 with the 1 ton axless for 800 bucks. truck was a rotted turd so just scrapped it and made a couple hundred back. there are deals out there just have to look around.

i ran 38s on 10 bolts for years but carefully. not only do you have to worry about axle shafts breaking you will be replacing ball joints and tie rods every year