I have a 79 it 175f and was wondering what engines would be a direct swap engine on bike currently is toast 

1978-81 DT175, MX175, or DT125 will bolt right in... would need the carb from the new engine and carb won't fit the IT airbox hose... exhaust should bolt right up. IT ignition could be used. Skid plate might not fit clutch side without trimming. You'd need to use engine sprocket and spacer from IT (520 chain) or swap to DT rear sprocket (428 chain) from above bikes which will bolt right up to your IT hub.

The above engines will also have tach cable drives and oil pumps which you'd have to cap (tach) and remove (pump).

What's wrong with the IT engine? Might be easier and cheaper to fix IT engine... and would have a LOT more power.

(A couple of years of YZ125 engine would also fit but those are really hard to find in decent shape. There are a lot of that era YZ125's running around with the DT175 engine.)

It engine is locked up