The -151, -161 and -181 have the same airframe.
Archer (181) is different firewall forward (engine, cowlings, spinner, prop). Back seats are different.
Early -151 had a different aileron set up with dropped hinges and linked to the rudder. Later -151 were identical to the -161 except the engine.
As others have said, earlier spats/leg fairings were much smaller and didn’t fully enclose the wheel or undercarriage leg.
Last edited by smarthawke; 25th December 2017 at 09:30.