Joe --

1. In the US, 1974 was the last year for the 140 body style, and '75 was the first year for the 240 style (I owned a '75 244 and a '75 245, and also a '74 142 and a '74 145).
   
   
2. The standard engine was the B20F engine, which was also used in the '74 140s. This is an interesting pushrod engine -- it was a "bridge" engine between the earlier B20 pushrod engine and the upcoming B21 OHC engine (introduced in '76). The B20F engine in '74 and '75 used K-jet FI (whereas the '73 B20 used D-jet) and had the same 8-bolt crank and flywheel as the future OHC engines. I once used a flex plate and ring gear from a '74 140 on an '87 740 turbo. Perfect fit, perfect function.
   
   
3. Not quite a "one-year wonder" but a "two-year wonder," as explained above.
   
   
4. Whether it's a '74 car or a '75 car, if it has the B20F pushrod engine (8-bolt crank), it's a strong engine. One of mine was seriously warmed up and it ran very well. I think one tiny difference between a '74 and a '75 engine is the distributor -- '74 had points (I think...) and the '75 was pointless. So to speak.