Some help needed

[Lasse Sweden]

Hi I have a GMC 100 (2)1955 I want change gear in rear axle if I understand right I have H 033 GM SS . Have today 3,90 I think and see maybe 3,38 fits problem is I don’t now where to order so I get right, if anybody can help me order number and company , are living in Sweden so most be right first time when I order

 

[Bill Hanlon]

Hi I have a GMC 100 (2)1955 I want change gear in rear axle if I understand right I have H 033 GM SS . Have today 3,90 I think and see maybe 3,38 fits problem is I don’t now where to order so I get right, if anybody can help me order number and company , are living in Sweden so most be right first time when I order

Even though our host's web page here Rear End Gears-3.38 Ratio-Classic Chevy Truck Parts says "Chevrolet only", I believe their 3.38 gears will fit all 1955.2 and some 1956 GMC 100 series trucks. In '56 you could get an OPTIONAL Spicer 45 rear axle in the 100 series GMC trucks. The Spicer axle became standard in 1957 for GMC. Chevrolet stayed with the H033 into the 1960s. The H033 has a round rear cover, while the Spicer rear cover is not round.

Changing out the gears and properly adjusting clearances and backlash is not something for the do-it-yourselfer to try himself.

 

[Lasse Sweden]

Thanks Bill, rear cover is round and I have put a picture on that to , better to ask you people over there who now best regards Lasse

 

[vwnate1]

Let us know how it goes .

The ring gear will have both ratio and GM P/N on it, might be helpful to post the GM P/N and how many bolts hold the ring gear to the carrier......

More info helps those who know this stuff better than I, what to tell you .

I assume you have a V8 engine ? .

 

[Lasse Sweden]

I have 6 cylinders engine, sounds like I have one gear missing when I drive in 4 gear(hydra magic ) that’s why I want to change gear in axle. We have winter here now and the truck is in a garage so I wait 3 months before I take the truck home and take out the gear from axle .

 

[Bill Hanlon]

What size rear tires?

 

[Lasse Sweden]

What size rear tires?

What size rear tires?

What size rear tires?

235/75R15

 

[Bill Hanlon]

215/85R16 would only decrease RPM by 10%. Probably not worth the money.

 

[Lasse Sweden]

215/85R16 would only decrease RPM by 10%. Probably not worth the money.

I have to wait until i get the truck home again and take out the gearing and see if there are any numbers on it

 

[Lasse Sweden]

Hi Bill perhaps you can help me . Pinion number is 3740874-10-39 gm Ring 3697702 GM . I can not find anywhere on Google if 3,38 pinion and ring fits When i looking on Yukongear YG GM55T-338 there are no data about measure on bearings so i can no go that way to find out if it fit . Perhaps you have an idea how to find out Best regards Lasse

 

[Bill Hanlon]

The -10-39 is the ratio, 3.90 to 1. Given that you have a 2nd series 1955 GMC 1/2 ton with a GM corporate H033 rear axle this Rear End Gears-3.38 Ratio-Classic Chevy Truck Parts should work. I'd call ClassicParts and see what they say even with the "Chevrolet Only" warning. Also consider Rear End Gear Installation Kit (Complete kit)-Classic Chevy Truck Parts