91 RS Drop Top

My 91 RS has a 350 in it with the original TBI. I have had tons of trouble finding time to work on it so I asked my mechanic to find the casting numbers for me while he was working on some other stuff. I know that sounds lazy that I couldn't find time to find the casting numbers, but the military keeps me really busy. He said he got the numbers off the rear of the block, but when I look the numbers up on mortec.com and other sites I can't make sense of them. Can somebody help me out?

Here are the numbers the mechanic gave me, in the order he wrote them down:

XU3E 6015 AB

Any help is appreciated. I'm trying to not only confirm that it is a 350, but hopefully find out what it came out of so I can get specs, roller or flat tappet, etc.

AlkyIROC

Casting numbers don't have letters. I have no idea what those numbers mean.

Your engine should have 5.7L or 5.0L cast into it also which makes it easier to tell if it's a 350 or a 305.

If the engine is original, the VIN code will tell you what it is.

bigtgun3

the number you need is on the right side of the block right behind the aldanater they are hard to read some times if you buy the haynes book for the camaro it tells you everything you need to know they run like 15$

91 RS Drop Top

It is def not the original engine. I got a PM from a TGO member saying those numbers indicate a 69 pickup engine. Being that old would explain the lack of teh 5.0 or 5.7 stamping.