ORIGINAL: EASYTIGER
THe one you are talking about is the testors 8000, usually with a nylon crankcase...yep, it's not easy to mount!
The one in the pic is a Testor/McCoy/Wenmac, and they are fine little motors, I have one in a Scientific F4B4 c.l. job. I don't have any parts, alas, but if you check ebay complete engines are very easy to find, very, very cheaply. THey have almost NO collector value, nobody wants them, it;s a shame, because they were just fine. Lots of different variants on these, too, different starters, spinners, mounts, marks, etc...
The Testors 8000 was a follow-on to the one shown. In RTF form the 8000 came with either a metal or plastic crankcase. I have one of the metal ones. It was also sold with a tank and mount. These came in a box with prop, etc. The piston/cylinder and spring starter seems to be the same on the 8000 and the previous model (No. 2?).
Bill S. - you may want to hang on to them since parts can be used for other engines...or you may run across the tank version.
George