The LD-74 definitely is a ready made DIY platform, whereas the TM-80 would require a lot of finessing (i.e. fabrication..). But not a bad mic as is?
Thank you for the kind words on my photos.
Both microphones sound OK, especially considering their low cost. The TM-80 sounds nearly the same as the LD-74. I believe it is well worth the $29 US (including shipping) I paid for it. It is a nice body with a bit of heft (weight/mass) to it. Looks good, too.
The TM-80 MIGHT be an easy donor body, notwithstanding it lacks an internal frame like most other condenser bodies have. The replacement circuit board could "float" inside the body, perhaps suspended or wrapped with cloth, packing foam, or other appropriate material, being sure to ground the XLR Pin 1 to the body.
The only tricky bit is to make a 40mm circle of metal, plastic, circuit board, or other material for mounting the replacement saddle and capsule. Or, one might carefully remove the original saddle, and devise a way to secure the replacement saddle to the original circuit board, but that might damage the original circuit board. Therefore, I would cut a 40 mm metal or plastic disc to replace the original circuit board. One MIGHT make it from triangular piece of plastic, metal or even PVC board, drilling the mounting holes just inside the three points, as it may be easier to cut three straight lines than to cut a 40mm circle. It all depends on what tools and materials you have. I think this is the only tricky aspect to using the TM-80 body. (Easy to do than say it!)
So ... um ... it may not be as difficult as it first appears ...
Just thinking aloud. Good luck. James