gmax to airport260 and FsDYn conversion

Hi, I'm trying to convert a gmax (flying) model to Airport260 scenery.
FSREGEN asks to use makemdl.ex with the optin to keep all files, but the (new, with gmax) MakeMDL does not have it .
An older version I used did not produce the ..._0.asm file, which is needed, due to using an old MakeMDL.exe.
The real question:
How do I convert a gmax file (exported I assume) to a .APT or scasm file? (Most popular freeware please if poss.)
Can I (then) use it to make that model in FSDYN for dynamic scenery? Or is there another way to add a gmax modelto the FSDYN standard models, (e.g. the glider)
(I have also TTOOLS, and some DOS coversion programs that XP does not like) Thanks for your past valuable help!
FSREGEN asks to use makemdl.ex with the optin to keep all files, but the (new, with gmax) MakeMDL does not have it .
An older version I used did not produce the ..._0.asm file, which is needed, due to using an old MakeMDL.exe.
The real question:
How do I convert a gmax file (exported I assume) to a .APT or scasm file? (Most popular freeware please if poss.)
Can I (then) use it to make that model in FSDYN for dynamic scenery? Or is there another way to add a gmax modelto the FSDYN standard models, (e.g. the glider)
(I have also TTOOLS, and some DOS coversion programs that XP does not like) Thanks for your past valuable help!