Some time ago Reverend Bob wrote ...
4AE, 4AF, 4AH, 4AN, 4AS, 4AW, and 4FL are interchangeable. Based on the FHF ebauche:
FHF 52, some with Breguet overcoil.
.... I have a Platinum 38 Diamond case in need of a working Bulova movement. Old (no name) movement measures 21 x 9 mm. I think the eubache for the 4 series movements above would work.
Thanks Ken S
The series has no fewer than 6 different ebauches, all with slightly different sizes. The ones based on the FHF 52 are 4 2/3 x 11'''. That would equate to 10.52 x 24.8 mm.
The ETA 746 (4AM) is slightly smaller, at 4 1/4 x 10''', as is the Peseux 90 (4AB) This would be 9.58 x 22.558 mm.
The only way to know for sure is to actually try them in the case. There is also the issue of the placement of the dial feet, which will vary depending on the movt.
Precious metal models don't always have a plated equivalent, especially with ladies models. My theory is that some of these were a special production run, including one-offs. This practise continues to this day.