C1 - Rear End Question

[Dick C.]

Out of a 1958 270 hp 3 spd, rear end AP 503 (possibly the 3 is a poorly stamped stamped on the outside of the carrier flange. The AP stands for 4:11, three speed which came out of a 1958 270 hp 3 spd. Is this the rear end for that car? The serial # of the car is J58S107275. There are other casting #s on the carrier.

[Dennis A.]

Re: C1 - Rear End Question

Dick...

Check the casting number...#374883 is a positraction used 57 - E61 if that helps ( #3725899 was Non-Positraction)

[Doug Flaten]

Re: C1 - Rear End Question

Isn't the 503 an assembly date code? Someone else can correct me if my memory is incorrect. But I would not think it is original to the car with that date stamp.

[Ted S.]

Re: C1 - Rear End Question

The "born on" date is May 21, 58 for your car. The AP503 stands for 4.11 positraction for 3 or 4 speed, assembled on May 3. This should be stamped on the passenger flat side of the carrier. On the drivers side there should be a thin P, a cast date code, the casting code. Make sure the cast date code is a '58 cast code and it has the correct thin "P". Assuming that checks out, I'd say it's original to the car. Ted

[Mike E.]

Re: C1 - Rear End Question

AP is the correct code for Corvette 4.11 with posi from 1957 through 1961. The 5 03 is assembly date of May 3, with no year designation. Next to the casting number (on the opposite side of the carrier)is a casting date, alphanumeric. (such as D278) That will tell you the date and year that it was cast.

[Mike E.]

Re: C1 - Rear End Question

Sorry for the duplication--Ted's message was posted while mine was being composed.

[Doug Flaten]

My mistake

I forgot the date was month and day, not month month year.