hey guys i just bought a 81 k5 blazer and am in the process of buying a lift but i can't decide what gears i should run with 35's now and don't even know what it came with stock. I was also wondering if any mods would be necessary for my driveshafts. Any advice would be helpful guys. Thanks. Steve  

If your only going to run 35's a 6" lift is going to look silly. on these trucks with that lift i know people who run 38 or bigger i would go with 4".  I would run 4.10 gears and with a 4" lift no mods to driveshaft would really be necessary.  

I do not know why people think 4.10 are such great gears with 35's. It is like it is some magic number or something. You need more like a 4.56 here with a non OD tranny if you expect it to run fairly well and have tranny last.Also with bigger tires and lift it is more than just the numbers when figuring gear ratios because a lift and tires add drag and it takes more power to cruise than before and PROPER gears level the play field a bit.  

I had an 82 k1500 sierra and put a 4" lift and 35" and I wish I went to a 6" lift cause the tires were rubbing on everything offroad except for the hwy the tires didnt. so to cure that I trimmed a little and downsized to 33" tires. Now a 6" lift wont look silly on a k5 w/35"s. thats a good choice but the gears should be a min of 4.56 or you could run 4.88. 4.10s would put strain on your drivetrain and you want it to run as "FREE" as you can.  

if you run a 6" lift with 35's you will have alot of space. i have a friend with a 86 blazer, 4" lift, 35's and even he has space left over with no trimming. 4.56 would be good gears to but 4.88 is a little high with 35's.  

Lemonhead:
if you run a 6" lift with 35's you will have alot of space. i have a friend with a 86 blazer, 4" lift, 35's and even he has space left over with no trimming. 4.56 would be good gears to but 4.88 is a little high with 35's.

With a non OD tranny, a 4.88 would be a bit deep with 35's maybe but with a OD tranny 4.88's or better still 5.13 would be sweet because you would cruise at a lower RPM in OD with 5.13 than with 4.10's and no OD and have a LOT more guts in lower gears too. Low Range would not be needed most of the time.  

yeah the tranny's a 4 spd with granny low and thanks guys i appreciate the insight.  

I could be wrong, happens a lot, but if you had 35" tires and 5:13's your RPM's would be higher in any gear than if you had 4:10's, right?  Please explain if I'm wrong.  At least you are not runnin' 35's with the stock 3:08 with close to 400HP.   My tranny hates me. (transmission that is).  

I would go 4” my truck is 4 with 35s if it was bigger it would not look rite if I go to 38s I am just going to get some cut out flares because my truck is already pretty tall also I would get a set of 4.56 I have ran 4.11s on a hot rod with 28” tires there low with that short of a tire but with 35s there a little tall.  

Hey Big_Blzn are you running any type of a stall converter in your transmission. You want to feel your motor come alive install a big stall converter there like NOS it would be a shame to have 400 HP and no stall.  

joepeterson:
Hey Big_Blzn are you running any type of a stall converter in your transmission. You want to feel your motor come alive install a big stall converter there like NOS it would be a shame to have 400 HP and no stall.

High stalls suck off road and make a lot of extra heat and lower MPG around town. A stall is no substitute for gears in a 4x4.