Now you remind the old grey sells I remember the suretrac but as you say they dissappeared.
Millers will be pretty expensive, I used Carlube stuff in mine, probably wouldn't put it in a rally car (can get Sikolene Syntran 5 at good prices for those) but fine for the Maverick. Might go to Castrol B373 for the rear diff next time for extra lock up, but its not really a road oil, but mines not really a road truck either.
Where you from btw and who's your local AP man? Alan Brown?