Ive heard that they do, that they dont, that some do and some dont.... Anyone have a definitive answer?

Per GM specs the '66 360 hp L34 would have a forged steel crank. Per "Chevy By The Numbers" some '66 360 hp had 2 bolt blocks and some had 4 bolt blocks.

mine is a #962 block,4 bolt main,Dec'65 build.

The DEFINITIVE answer has been given IMO.. 66 360 hp blocks could be had in 2 bolt 961 variety ( more common IMO ) or 4 Bolt 962 Variety.

and ALL 1966 396s had steel cranks (325, 360 and 375 HP), '65 and '67 too... '68 396s also had steel cranks, but not sure if that ended mid-year, or maybe '69 MY...

From the blocks I have seen, alot of the early 360HP motors used the #962 block (4bolt only) somewhere in late Dec of 65 they switched over to the #961 block for 360HP motors(2bolt till approx. May 66 then could be either). I have seen have 2 "EF" blocks with assembly dates in the first week of January that were both #961 2bolts. I cant recall seeing an earlier #961 block with a 360HP rating. I have seen 50 or so 360HP #962 4bolt blocks, all dated Aug-Dec of 1965. I have yet to see a #962 4bolt with a Jan-July 360HP deck stamp,the only #962 blocks I have seen after JAN have been the "EG" 375HP blocks (unless they were decked). This would be an interesting question for Diamond Judge as to when and why they switched over from 4 to 2 bolt main. I belive it had something to do with the introduction of the 375HP motor.

and ALL 1966 396s had steel cranks (325, 360 and 375 HP), '65 and '67 too... '68 396s also had steel cranks, but not sure if that ended mid-year, or maybe '69 MY...
Starting in '68 the L35 396 325 hp had a cast crank. I had one. The L34 and L78 still had a steel crank.

Awesome, guys. Lots of good info. Thanks a ton.