The C3AE-6015-H was the service block for the 62-63 390 PI. It's a hyd lifter block and is the service replacement for the C3AE-6015-E solid lifter PI block. The H block was used in either std 390 or 390 PI applications as a multi purpose block as it was drilled for hyd lifter oiling. The lifter oil galleys were plugged if solids were ran...or not. The 6015 number is just the casting number for a std production block. Serivce blocks used a 6010 part number. The Thunderbird VC's came on all FE's back then not just the Tbirds. It's also very possible the H block was a regular production block then after. My resources indicate a service part tho. But the best was to tell is grab the date code off the side of the block and compare it to the head and intake date codes. You can also check the blocks final machined date on the left ear by the head deck. That is stamped in after the blocks are machined. The blocks date code is on the left side above the oil filter adapter. The head date codes are under the VC area between the center 2 valve springs. Intake date code if iron should be by the thermostat or dizzy area. If aluminum it may or may not have a date code. What is the casting number of the heads? It's between the center 2 spark plugs. C3AE-6090-C?

G.