I did some deep diving through various Chevy Master Parts Books, a 1963 Delco Moraine Hydraulic Brake Parts Catalog and some web surfing to find out the following:
Original Casting# = GM Part# 5455482 for a 7/8" bore front wheel cylinders used on 1954-59 1-1/2 and 2 ton trucks. Same part for both sides. I found one
NOS GM# 5455482 in this evlbay ad. The 2nd picture in the ad confirms the casting is a 7/8" bore, but the item looks pretty rough and I'd question condition.
A search of the Delco Moraine 1963 Catalog lists the front wheel cylinders for Late 1954-1959 40 thru 60 Series Models 1-1/2-2 Ton as "W19944", which cross references to the later Raybestos replacement # "WC19944". A look at the wheel cylinder specification details confirms these are 7/8" bore units.
I found one evilbay ad for an
NORS Raybestos WC 19944 wheel cylinder, and a second
RAYBESTOS WC19944 WHEEL CYLINDER. Although neither of these ads confirm the bore size, you could contact the sellers to ask for further confirmation before deciding your next step.
Lastly, Kanter lists a
WC19944 Wheel cylinder, but indicates you should call to confirm vehicle application and fit.
Best of luck getting what you need.
