Wad are the best fully mechanical slr camera ? Looking to start film photography
If I recall correctly, since you posted on Sony/Minolta forum, the only Minolta camera that fit your bill are SRT series. Those are very old but solidly built. Yes, it is fully mechanical. Works without batteries.
If you are looking for film SLR cameras that are manual focus, you can find them in used condition. Better bodies amongst the many models are XD, XE.. series. These requires batteries else it's default mode.
The above mentioned series use common SR mount but later Minolta lenses have features built in that enables more functions that were found on newer bodies. You need to read up a little on the differences between MC and MD. Both are SR mount but with add on features.
Finally, if you are not interested in manual focus BUT interested in film photography using AF, then get the Dynax 7 series. The lens mount has changed and not compatible with SR mount. They are A mount as Sony acquired the digital camera business from Konica Minolta. The lenses are fully compatible with Sony A mount cameras, not to be confused with E and FE lenses.
Read up on Dynax 7 and discover the many interesting features built into the camera.
Hope this helps.