quick 512 TR diff question

Based on the comments of Robert Hayden(uzzsoarer) to myself after sending him pics of my cover-off diff pics not antiquating with the ZF 'weld it all' images I had become aquanted with... "Mate! you have won the lottery! that is an 512M diff you have in there"
Hope this helps.
Pete K.
WA

 

Later 94 only

 

512M was the only Testa with the updated Diff that I know of.

 

SB 30-23 describes the new forged differential housing, part number 155099 that was incorporated in the 512TR somewhere around the 1994 model. It replaced the previous welded type. Checking the gearbox serial number will indicate which housing your 512TR has. The SN break is 1370 and later. Another improvement was made at SN 1513 whereas a later ring gear mated to the differential with dowel pins and bolts of finer thread than previously. My 1992 has gearbox SN 314 which is much prior to the forged differential. The SB states that the forged differential will also fit the Testarossa but does not mention the Boxer series.

SB 30-23 also announces a new, stronger bolt to attach the ring gear to the differential. It is the courser thread allowing you to retain the older ring and pinion gear and could be used with either the welded or forged differential. I had planned to install these bolts when I do an engine out early next spring, but my fear is increasing enough about the welded differential that I may replace it also.

SB 30-18 describes a new heavier propeller shaft incorporated in the 512TR commencing with engine number 31108. My engine number is 29896 so this probably occurred in 1993. The propeller shaft is what was previously pictured and referred to as the quill shaft. It transmits power to the transmission from the gearbox attached to the clutch housing. When I had the gearbox off to work on the throwout bearing this shaft slipped right out of the transmission. The female end goes in the transmission and male into the rear gearbox. The earlier shaft was 17 mm diameter while the improved shaft #151651 is 20 mm diameter. If my calculations are correct that is 38% more mass to the diameter of the shaft. The new shaft will fit the Testarossa and the 512BB according to the SB.