Unless it's an early 60's til when Steve said (close to 1970), there's no difference, so don't be fooled by any Ebay listings saying a 70's high dollar B/O version is the "magic" time period, building it up with "Bonham", or any of that stuff.
I saw a '72 or '73 6.5 402 go for over $800, and at point they were going for $399 brand new!
It's the same drum today as it was back then.
I also saw a NOS (new old stock) 1979 go for $1000. Same drum you could buy today!
If people buy the hype, good for the seller I guess (buyer beware and all that), but it's the same as it's been for ages.