I'm looking for a set of gears for my Camaro that uses the 7.5" GM 10 bolt and I believe the S10's and Blazers had the 7.5" 10 bolt as well with I believe a 3.73 gear? What other models had them and what all ratios were available?

s series, monte carlo's, grand prix (fs), cutlass, regals, malibu's, ta's, monza, vega, luv.

3:73's are really hard to find. most s series trucks used a 3.08 gear (manual) and 2.73's (auto)

the worst part is if you have a icky gear series 2 carrier (3.08 or lower) you cant use higher than 3.08's without a spacer or thick aftermarket gears. that adds another $50 to the cost (used gears are around $80- i just bought some for a 8.5)

so for $20 more you get new gears that fit right and have a warrenty. ive killed many a 7.5 in my tenner days at the track. i have no love for it.

I have a 2 and a 3 series carrier. My old axle is a 2.73 geared one. I bought another complete axle with busted 3.42's and had it rebuilt with another used set of 3.42's. Now I want a little more gear and I think 3.73's are the highest you can get. I thought they were more common than the 4.10's but I guess I was mistaken.

3:73's are really hard to find. most s series trucks used a 3.08 gear (manual) and 2.73's (auto)

I've actually never seen 2.73 in an s-series, not saying they don't exist though. 2wd s-series were generally geared higher, numerically lower, but not that bad. my 4.3 auto s10 had 3.08s. Most 4wd blazers with a 4.3 will have 3.42s, and 2.8s and 4cyl commonly had 3.73 or 4.10 in both 2wd and 4wd. Cars would be the hardest to fins a 3.73 ratio in probably. Hit the junkyards and look for the RPO code you need.
3.08 = GU4
3.42 = GU6
3.73 = GT4
4.10 = GT5
4.11 = HO4

s series, monte carlo's, grand prix (fs), cutlass, regals, malibu's, ta's, monza, vega, luv.

3:73's are really hard to find. most s series trucks used a 3.08 gear (manual) and 2.73's (auto)


3.73's are very common with the 4-banger and 2.8L S-trucks. I have yet to see anything taller than 3.08 in an S-series (and that's usually a 5spd 4.3L truck).

my 83, 87, 91 and 93's all ran 3.08's. 3 were 4's and 2 were 2.8's

Must be made-for-Canada gearing :p

I think we wrecked over a 100 1st-gen s-series while I worked in auto wrecking. I side with Jamus's findings.

4-banger: 3.73 or 4.10
2.8L: 3.42, 3.73
4.3L: 3.08, 3.42

Astro/Safari also used the 7.5"... 3.23 shows up there sometimes.

so i'm guessing my best bet is to search for an S10 with a 4 banger, any certain years to shoot for?

My
'87 2.8 has 3.73
'93 4.3 has 3.73
'00 4.3 has 3.42
all of them are auto trannies.

My
'87 2.8 has 3.73
'93 4.3 has 3.73
'00 4.3 has 3.42
all of them are auto trannies.

Good info, I guess the search continues!

thats funny, cause my '86 4wd auto blazer has 4:10, and my '87 manual 4wd s-10 has 4:10's as well...

Astro/Safari also used the 7.5"... 3.23 shows up there sometimes.

Man, how could I forget about that, I drive one of the dang things.

There's no exact rule on the s-series gearing. Just like any mfg, they mix and match what they use. I would say to start looking in the early ones, say 82-87, 4cyl first then move to 2.8.

One other point....

The 7-5/8" was introduced starting in '88, but the 7-1/2" didn't disappear until 93-94 or so. I'm not sure how much interchanges. The axle spline (26 vs. 28) is the main difference I'm aware of.

One other point....

The 7-5/8" was introduced starting in '88, but the 7-1/2" didn't disappear until 93-94 or so. I'm not sure how much interchanges. The axle spline (26 vs. 28) is the main difference I'm aware of.

All I need are the gears so if the gears are the same i'm good, otherwise i'll need to know how to tell them apart so I get the 7.5" gears!

My Mom's 89 2 door S10 blazer with the towing package had 3.73s. It blew them out once.

My 89 S15 2.5L/2wd T5 had 4.10s.

My 89 S10 2.5L/2wd T5 had 3.73s. I blew several carriers out of the back of this one (383 under the hood).

My Mom's 92 4 door S10 Blazer has 3.42s.

I've never seen airplane gears in an S10.

Hit the junkyards and look for the RPO code you need.
3.08 = GU4
3.42 = GU6
3.73 = GT4
4.10 = GT5
4.11 = HO4


This is still by far the best way to tell what gears are in the truck. Provided it has the original axles.

This is still by far the best way to tell what gears are in the truck. Provided it has the original axles.

That's usually what I look for in the cars too but that's assuming they haven't been changed.

All I need are the gears so if the gears are the same i'm good, otherwise i'll need to know how to tell them apart so I get the 7.5" gears!

The 7.5" and 7.625" gears are interchangeable. There is a difference in the carrier series as well as the 26 to 28 spline change as mentioned. If you go with new gears you can get 4.56's :D. Think about how small those pinions would be! LOL

The 7.5" and 7.625" gears are interchangeable. There is a difference in the carrier series as well as the 26 to 28 spline change as mentioned. If you go with new gears you can get 4.56's :D. Think about how small those pinions would be! LOL

I have the carrier so that's not a concern. I also have a series 2 and 3 so I have most (if not all) gear ratios covered.

I saw the 4.56's at jegs and thought about it. I know the 4.10's are weak, I can't even imagine 4.56's!!! But that gear would be SWEET from a stoplight!