Dev times with DD-X and earliest TMax 400 code TMY

Hello there, I recently shot a roll of expired TMax 400 in its earliest emulsion design, code just "TMY", which has different times to the current 400TMY-2. Given the film condition, I'd rather use DD-X than D-76, but the problem is that Kodak's data sheet from the time doesn't list DD-X, and I can't find any older data sheets for the developer. No, I don't have any more rolls to test and yes, I know I was irresponsible by not conducting a test strip before shooting the roll, but here we are. Could someone here give me a hand?

Thank you.

According to my downloaded Kodak pdf files, there isn't much difference in developing times for old and new TMax400 in TMax developer at standard dilution. For example, for a small inversion tank at 20degC, 7min for the old TMax400 and 6.75min for the new TMax400. You could apply this ratio (0.96) to a different developer which is something like TMax developer such as DDX. I would hazard a guess that any inaccuracy in making this assumption is likely to be less than the variability due to the film's age, not to mention your metering style and how contrasty the light was. I hope this is a bit helpful.