Several sources agree on 71000G.
Seattle Times 1989-11-13 says "three cracks, including a 9 footer,
sprung in the bottom of this 173,000 tonner".
This is unconfirmed.
This apparently was the spill that triggered a new USCG policy.
In March 1989, Coast Guard sent a letter to Alyeska saying
that from now on, ships with cracks would not be allowed to load;
if already loaded, they would have to unload.
Not sure if this was really enforced,
but cracking has been endemic to the Alaskan trade fleet.
Anchorage Daily News 1989-03-14 says 36 spills in Aleyska records at Valdez between 1977 and 1989.
Seattle News article claims Stuvesant spilt 600,000G in January 1987 in Gulf of Alaska "17 foot long crack"
and another 700,000 gallons in October 1987 from an 18 ft long crack.