I have a 86 k5 silverado package with a 305 . I've been wondering what gearing i have. I took a look in my glove box on that sticker and it says it has 3:73. Does this sound right cause i've been told that aint right.

 

3.73's were definitely offered in your year. If it says you have 3.73's, then you likely do. You could check it either by turning both wheels on an axle 1 revolution while counting the revolutions of the pinion shaft or by popping off the diff cover.

 

hopefully. all the axles i ever get are 3.08s or 273s ive only ran across one 373 ratio and held on to it

 

3:73s were very common in fullsize chevy 4x4s... even in the mid 1980's...

 

yea, i was told i had 3.08s. but the sticker said i had 3.73s. Im gonna get rid of them here pretty soon anyways and put 4:10s cause i dont thinik 3:73s will be able to handle 38's. What yall think?

 

I have 3.73's with my 33's and they are decent. 3.73's with 38's would lug bad. 4.10's might even lug a bit too much for my liking. If you can swing it, I'd go for 4.56's.

 

for the 38" combo, i imagine you have a 700-R4 transmission??? or manual... if its the overdrive tranny i would look 4.56 and up... either 4.88 or 5.13... i have the 5.13 with my 40" tires, and with the OD trans.. it feels right.. not lugging at all... and very nice outta the hole...and the overdrive will keep it from tacking 5000 RPM's while on the E-Way ...

Ck1500

 

I have run 38"s with 3:73s many times on full size Blazers and Suburbans.
It works fine as long as you got the torque to pull em around (decent 350 / no high rpm racing cams). I always ran a 350 with a TH350 or TH400 tranny (no overdrive).
I have also ran 38"s with 3:08's and 3:42's and yes... that does suck... My choice with 38"s would be for 4:11's if not running an O/D tranny.

 

Well the tranny was just rebuilt (700r4) with heavy duty clutches, springs, etc and a **** kit. Unfortunately there is only a 305 with a 4 barrel 750 carb, that i know of cause i just bought the truck, so yea theres no torque behind it.

 

Yea again it can turn them with 373s if you got some power. Just gonna strain on the trans. Good highway rpms though