When it comes to Modular Engine blocks, you'll find there are as many as 12 different castings, but the basic architecture is the same so any heads will bolt up. For performance applications i recommend finding a 1996-up block because these (Romeo and Windsor) have cross-bolts used on all five main caps. Windsor blocks use dowels, and most Romeo blocks use jackscrews, neither have proven to be stronger than the other. Most have found about 10 different cast numbers for blocks (from 1991-present), some are better than others. The Romeo plant built the first block, which was the F1AE, and it was used through early 1992. It was replaced by the F2VE casting at the same time Ford released the AODE transmission in RWD cars. This block was superseded by the F4VE, which is identical to the F2VE. All three blocks are virtually the same and have hollow dowels to align the transmission. The next block in the long lineup is the Romeo-built F65E, but Ford also cast the F6VE and the F7VE. All three blocks are visually and dimensionally the same, have cross-bolts on all five main caps, and were used from 1996-98. There is a threaded hole in the cylinder valley for a knock sensor. These blocks are preferred over earlier blocks and will work in all RWD cars. The Romeo plant also built engines with a F7AE and XW7E casting number. They were primarily used in trucks from 1997-99 but can be used in passenger cars. Production of the Windsor blocks began in 1996 with the F65E-BB and the F75E. Windsor blocks have cross-bolts on all five main caps and the bolt pattern on the front of the blocks is the same as earlier Romeo blocks. However, some of the holes may be 10 mm instead of 8 mm. This is important if you are purchasing a blower because the compressor bracket attaches to the front cover.