I have a 1972 Yamaha 175cc but the frame is hosed, there is a local person selling a 1975 Yamaha 175cc as parts. Will the engine of a 1972 Yamaha 175cc fit on the 1975 frame?

Sorry, no.

In 1974 the 175 frame was a complete redesign.

thank you

Where are you located?

I believe you could use a CT2 or CT3 frame. The Ct3 will have a steering column lock.
The CT2 engine will bolt into a AT2 or AT3 frame, but there may be a few differences in the battery box mounting, flasher mounting, etc.

Im located in Utah, i found a frame few hours south of me and went and picked it up. SN starts with CT1-119 and mine is CT1-130 and all measurements are the same. I picked it up for $50 its in decent shape little rusty and looks like someone welded an attachment or something because its the only thing i can tell that different between the frames, see attached photo.
I do have another question my rear wheel the spokes are shot and he had one off a AT1 that was same size but when i got home noticed the Sprockets are different sizes. My hub fits just fine in either so can i just swap sprockets?

I believe both used the #428 chain, so sprockets should swap back and forth easily.

The bigger rear sprocket will slow the bike down, the smaller one will speed it up.

By the VIN, both are CT3 frames.

You can remove the large snap rings on the wheels and swap over the whole sprocket hub in seconds. No need to remove the sprocket bolts.

The reason I asked where you were...I'm in Casper, WY, and I have a CT-2 frame my wife wants off the back patio. But I guess she's SOL, huh?

well crap i should have not jumped the gun that would have been a fun road trip too only i think 6-7hrs from me. Well let me see how everything fits on the frame if it doesn't fit right might still be needing one