TRE makes electric and air lockers for the R230 diff ; )
Reminds me, I have to go update it on the vendor thread in the General section. I have both the M205 and R230 for 3.37 and lower gear ratio on order through TRE. Probably a few more weeks for the M205 and a few months for the R230 since I apparently was the first one to order the 3.37 and lower gear ratio model TRE had to get a hold of a 3.37 diff. It was a hard decision between electric or air, but I figure since cars, tools, gadets, etc are going all electric, I may as well go electric for the lockers as well.
The American seller(Zepka Customs) for TRE USA is based out of Wisconsin I think and responds in a timely manner on Facebook messenger if you'd like to inquire.