This is GMC info for what they call a FH030 driving front axle on a 1/2 ton chassis. I don't know if the Chevy parts are the same.

RH wheel brake cylinder. 1958-9 GM part number 3741926
LH wheel brake cylinder. 1958-9 GM part number 3741925
RH wheel brake cylinder. 1956-7 GM part number 2352833
LH wheel brake cylinder. 1956-7 GM part number 2352834

I found THIS looking for 3741926, but the picture doesn't look right. Then I looked up the Dorman's W41718 that this page referenced. Again the picture looked wrong and it did not mention the Chevy or GMC 4wd trucks.

I had no luck searching for the other 3 numbers.

Additional info from the GMC parts book shows that each 56-57 4wd front wheel cylinder used 2 different sized pistons, while the pistons in the 58-59 wheel cylinders used 2 of the same pistons.

Last edited by Bill Hanlon; 10/22/2026 3:12 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.