Got a short deck big block on the stand. It came out of a 71 Challenger R/T, and according to the seller, it was original to the car. Build date on the block is June 7, 1971. Block has been decked so numbers on the pad are illegible. No VIN stamping is legible on the pad either.

Pistons are .060 over for a 383 (Speed Pro L2315F). Checked the bore, and it comes out to 4.310.

Stroke comes out to 3.38, so it appears to be a 383.

Here's where the fun comes in.

Casting number is 3614230-5. Block has the stiffening ribs for a 400, and the hump on the bellhousing mount for a 400. So for all intents and purposes, it's a 400 block. It even has the thick main webs of the early casting 400's. But the cylinders are bored for 383, and there is no sign of any sleeving being done to get .060 over 383 pistons in a 400 block.

Anyone ever see a block like this?