For so long, i was dreaming that my e21 320/6 was a 5 speed. And as of 20/6/2004, the 4 speed Getrag 242 gearbox, has been changed to a 5 speed Getrag 240 taken from e30 320i.

There're also other option like Getrag 245 from perhaps later e30, or a Getrag 265. Ideally, try to get 5 speed gearbox from e21 with 5 speed together with the propeller shaft.

Getrag gearboxes, come with either 4-bolt or 3-bolt output flange. Typically Getrag 242 came with 4-bolt outflange. To my suprise, my e21 getrag 242 (year 1982) came with 3-bolt output flange, i suspected it was a 4-bolt type. This is important, because later Getrag gearboxes came with only 3-bolt output flange. So need to match this with propeller shaft flange accordingly.

Technically, rubber mounting (Guibo) for 8-bolt is slightly thicker than 6-bolt. Also, 242 gearbox is shorter that 240, but 245 or 265 i believe is a little bit longer than 240. This information is important when we need to cut out the front portion of the shaft.

Based on the above, the front shaft of the propeller shaft was cut and re-welded with the 3-bolt flange such that the overall length difference is about 1.5".

Whereas, there's no change to the rear shaft.