Nothing against Moss, I use them all the time. But I usually place my Moss order (especially big $ ones) through lbcarco.com, a volume dealer. He gives a substantial discount (~15%) on all items, all the time. Click search on the page, then enter parts numbers, TRF parts too.
Part number Description Retail price Our Price US$
520-500 SPEEDI-SLEEVE, DIFF PINION - TR2-6, MIDGET, MGA, BANJO MGB 37.95 32.26
520-505 SPEEDI-SLEEVE, TIMING COVER - TR2-4A TIMING COVER 39.65 33.71
Not sure if you knew this already or not but there are several dealers that give these discounts. Just trying to save you a few bucks, Moss et al. still get their share too.