[rjahl]

Originally Posted by cheerio

Interesting to see the LCI 530i and late E90 335i use 6HP21, while all 325i/328i are listed with the 6HP19.

I'm toying with the idea of installing the 6HP21 from an LCI 525i, but that would take extra work to figure out the electronic shifter.

I know that the TCU in the newer 6HP19's has better tuning options, but is this related to 6HP19 vs. 6HP21?

It's a bit confusing but at some point around 2007 ZF upgraded the 6HP 19 with additional clutch plates and upgraded magatronics. 6HP19 TU. It shifts faster and manages toque a little better.

BMW called this the 6HP19TU while ZF called it the 6HP 21.