I think it was HEH-CF, while the Mk1/Mk1A toploader is HEH-E. The critical differences are:
– The gear ratios are different. The Mk2 Tiger’s first gear ratio is 2.78 to 1 while the Mk1/1A is 2.32 to 1. The general consensus is that the wider mk2 ratios produce a more street-drivable car especially if you’ve still got the 2.88 rear end.
– The front ears on the case match the wider bellhousing bolt pattern that was adopted in 1965.
– The input bearing retainer has a slightly larger diameter. Dunno if the input bearing was also made larger. In any event, the input bearing retainer OD has to match the ID of the bellhousing.
– The bellhousings have the wider bolt pattern on the rear, a larger input bearing register, and the 6-bolt pattern for the engine block flange.
– The 5-bolt bellhousing clutch release cylinder mount won’t fit on the 6-bolt bellhousing. Since the Tiger’s use of hydraulic release lever actuation was uncommon, you have to do some searching to find a suitable mount or make your own. The other alternative is to use a hydraulic throwout bearing.
The tailshaft and tailshaft housing are not exactly unique to Tigers (I think) but they are somewhat uncommon. If you’re trying to build up a transmission from parts then it’s probably best to talk to David Kee at David Kee Toploaders or one of the other toploader specialists.