The transmission might still be in there, based on how level the engine is sitting - they could've pulled the shifter for another 4-speed - no guarantee, though. Missing tranny also might mean missing driveshaft, clutch, flywheel, bell-housing, clutch linkage, etc.
Looking closer I also noticed a few more things like the extra power steering pump (under the extra alternator), missing hood locks, rear air shocks (most likely to assist with the towing, but they're still tough on the upper shock cross-member). I think this car's been parked for a LONG time with parts coming and going - looks like it's been left in a corner of the shop (or outside) and stuff picked or dumped off with little concern - I know how that goes... I had a couple of really rough parts cars I didn't really care about as well.
The driver side export brace missing, passenger export brace not secured, chain still on the engine, and another PS pump bracket laying on top says "might not even be the original engine" to me.
Probably just an optical delusion, but it's hard to tell if there's even a clutch pedal (I suppose it could be hidden by the rim of the steering wheel... but to me it looks to be missing as well).
Yeah... I suppose I'd consider buying it as well - but not for a penny over $2500. I don't care how straight the sheet metal looks, a lot of it needs be replaced (add "outer wheel houses" to the "quarter panels" note I made earlier).
