Ah yes, well this:http://www.vintagedrumguide.com/pearl_drumsets_1978.html

Anyone know what makes up the "wood" shells? And for the composite shells, how many plies of each material?

there's this, but doesn't speak to that issue specifically:http://schniederslm.hubpages.com/hub/pearl-drums-2

There is a full range of catalogs on the Pearl drummers forum from memory.

A lot of the early Pearl wooden drums, my 1964 20" bass drum for one, were made from very thin Lauan plywood.

Don't know about the fiberglass shells, but I have a phenolic 22" President bass drum. No plies as such, just a cylinder of phenolic material.

It would be easier if you had a specimen you could ask us about (a particular kit you are looking at/your kit you own now??)

By 1970 they were using the thicker Luan shells, commonly 6 or 9 plies - with no re-rings. Re-rings and the thinner shells indicate before they transitioned, which was about 67-68.

Battleship lugs were around early, then eventually the traditional Pearl rectangular spined lug we all know (perhaps the most common lug ever found on the side of a drum - too bad I don't like them!). But then again - the Slingerland-type may have that distinction - but there are several variations of those) I believe they were done with the Slinger-type by '70. Hex style mounting hardware was common until the mid 70s.

That's about it off the top of my head - but you have asked about a particular topic that there is a wealth of info on when you consult the catalogs - which are all easily found online. The Vintage Drum Guide has a wealth of these - a sister site to this one.

well, those catalogs just say they are 9-ply "wood" drums. I don't have a drum (yet!); just trying to figure out what's what so I know what to look for. I love the 3-ply 60's stuff but I'm really digging what seems to be thick 70's drums...it's all a bit mysterious still :)

But! I just signed up for Pearl forum so should get some answers there. Will report back

Pearl is such an old lady name. :-)

When you say you're digging what seems to be '70's Pearls, specifically how are you digging them? Does a friend have a set that you played and liked? Try them at a store? '70's recording artist known for using them?

If you give us details, we can probably figure out which Pearl sets to look for. Any details on wrap, lugs, spurs, tom depth, etc.

Post 3-ply, Pearl did some experimenting with shell material (as you know), so thick '70's Pearls could be phenolic (like my bass drum), fiberglass/wood, or plywood (plies most likely including, if not entirely, lauan).

I've run into these kits in backline situations. I can't guarantee they were all 70's but that was the impression I got (amidst my limited knowledge). Just recently I made a pilgrimage to Bentley's and he had a set of something in the back. I whacked the 12" and was like "yes! that's it". Definitely a 9ply something. He sent me this pic --

Fat, quick, warm thuddiness. I think the new Session Studio (birch/kapur) are supposed to capture this vibe. But...they're new, and I doubt they'll get the vintage tone

The drum pictured above...

I think this may be it, the "W-5" from 1978: http://www.vintagedrumguide.com/images/pearl_drumsets/1978_pearl_drumsets6.jpg

Wish I had better pics