TZ trans is an everyday trans
The value (for a TZ owner) in that part of the TZ drivetrain is in the bellhousing (all are magnesium and match the TZ motor's tilt) and in the transmission tail housing.
As Keith wrote, the TZ tail housing is unique with a vertical bracket attached across the back that ties (with a bushing at each end) to the tube frame. The circular casting that holds the single bushing on the standard 105 case is not there.
The claim to be a TZ transmission sent me to the TZ parts book.
The only .11 or .10 parts in the transmission are the shift lever and an optional 1st-2nd selector rod, fork and bolt (why?). Otherwise a TZ transmission is no different from the standard 105. And many TZs probably started life with the common street gearing unless they were immediately identified to be raced. My car, about eight-tenths of the way through the production sequence, did.
(Close ratio? The same gear set as the GTA, possibly lightened, which does have value.)
While the seller doesn't claim to have a TZ driveshaft, that's unique, too. Because the differential is bolted to the tube frame, and on the same plane, it's a single shaft with Giubos at both ends; no center bearing, no u-joints.
The u-joints, of course, are in the half-shafts.
Thanks to the Seattle seller for giving me something to comment on.
Richard B.
TZ #102