The recipient car for my M41 is now up on jacks and I crawled underneath to take stock. I noted first the shape differences between my long shifter tunnel and the donor car's short shift tunnel. The long shift tunnel slopes back linearly and becomes narrow more rapidly, while the short shift tunnel stays large further back then humps down more steeply right after the shifter. The obvious function is the make room for the short shift apparatus on the transmission. That short shifter assembly clearly wouldn't fit in my tunnel without alternation, which I was expecting, I'm keeping the long shifter.

However, it doesn't even appear that the overdrive unit itself will fit in my tunnel! If it does fit, it looks like it will be so close that it rubs. Is this true, or am I seeing the space wrong? Does an M41 in long shift configuration fit in the stock early model 140 series tunnels?