bmwe21.net forums

Does e30 manual gear linkage work on the e21?
Thinking of converting to e30 box, ideal would be to use e30 linkage.
Does e21 linkage bolt straight to e30 box if I can't use e30 linkage?

The clamp which holds the back end of the linkage is different so you will have to bolt it to the transmission tunnel. Make sure you have that clamp which holds up the back end of the gear linkage.. You will have to remove it from an e30 it's spot welded on iirc. The e21 linkage is totally different to the e30 linkage. Also the gearbox mount is different but I'm fairly sure it will work.

The gearbox and linkage is the same length so the gearstick will be in the same place.

Your problem is that the e21 uses a manual Speedo cable which attaches to the e21 box. The e30 has not got this provision so you will have to use a GPS driven Speedo which means a modified gauge cluster.

The e21 shifter plate and linkage will bolt up to the early e30 gearbox with the steel shifter plate (as opposed to the aluminium arm). I'm running one in my e30 at the moment as it suited where my gearbox ended up with my M30 swap.

As Nas pointed out, the speedo is the bigger issue! With my e21 I ended up with a 4 speed after finding that swapping to the electronic speedo is difficult. It is doable with an e28 speedo glued into the e21 cluster + chopper wheel from an e30 diff grafted onto one of the e21 axles - metric mechanic used to sell chopper wheels for this in the past, no idea whether they still do. GPS would likely be an easier route these days.