My '428' is a 390!

[FFR428]

Guys, the std 428 is a IU. The 428 CJ a IUB or "A" and the 428 SCJ is a IUA or "B". The A & B crank are the later version and should have the IUB or IUA on the #7 counterweight also. Different piston weights were the reason behind all the CJ/SCJ cranks. I have a 428 CJ "A" crank with IUB and "69" cast in. The 2U, 3U etc...are 390 cranks. No matter which one it is they all have a casting number or markings of some kind to ID it. G.

[FFR428]

Matt, the casting number is on the side of the block. Some service replacment blocks do not have a casting number. A helpful hint to help ID a block is the casting center it was cast at. DIF (dearborn iron foundry) and MCC (michigan casting center) are the two places these were all cast. If you see a "DIF" or "MCC" this is where the block was cast. The 428 and 427 stayed at DIF and the 390's and other FE/FT molds were moved to MCC in the early 70's where they were cast until production ended. MCC blocks are mostly 70's service replacement and production 390, 360 and FT blocks. Pre 70's FE /FT blocks, heads etc.... were all cast at DIF. So if you have a block with no casting number this can help ID it as you can at least tell where it was cast. Some 70's date codes start with a number with dot underneath. The dots were Fords way to tell 60's and 70's block appart. A number 1 with a dot underneath is a 71 block a 2 with the dot a 72 and so on....G.