SAE 90 in 64 Chevelle rear end.

[oldguy64malibu]

My shop manual calls for Multi-Purpose SAE 90 to be used in the rear end but does not say how much. It is a 64 Chevelle, not a Posi unit.
Thanks for your help.

[flash]

I take the plug out and fill as much as it will hold to the plug hole .

[Hank70SS]

I take the plug out and fill as much as it will hold to the plug hole .

Ya, not sure how much it holds but fill to bottom of filler hole.

[earthquake68]

It holds about 3 1/2 pints. (just short of two quarts) 80W 90 works just fine. No need to find a straight weight. For the record, 1/4" below the fill hole is technically full, but filling it to the bottom of the hole is perfectly fine.