They didn't make a 289 in '61. The 221 and 260, which have the same size and shape were a 62/63 motor (the 260 came out the same year as the 221), so I suppose it is possible they built this car with a small-block and someone upped it to a 289 at some point, which would have been pretty easy to do. Badges are easy to install as well.



There are two models of 289 (early and late) and the early has the bell-housing bolt pattern of the 221/260 and the later is what all small-block's and 6's had for years to follow.

I think the thing to do would be to do a VIN research on the car and see what that ciphers out as... though it may be a really special order thing that may not turn up in a VIN search.