Velvet Drive -aluminum case/housing?

I am almost sure my ford/bw bell housings (3 at last count) are all aluminum.

Here's the scoop, maybe not exact but as i remember.... I worked for Great lakes Power in the mid 80's which owns Paragon Gear works, I came in at the tail end of the transmission fiasco that Paragon was involved in along with Borg Warner, Hurth and possibly other transmission manufacturer's.
Anyways Paragon was asked to develop a transmission for the ski boat market, it had to be lighter than your traditional borg Warner and also requested was a down angle transmission so the engine could sit in the stringers parallel.
Paragon did develop a transmission and during the testing Phase we had bearing problems and failures, hundreds of thousands of dollars were spent on that project and the CEO. knew that hundreds of thousands of dollars were still needed and the CEO decided to scrap the project. Borg Warner also developed a transmission and they also had many problems at the time.
Hurth beat everyone to it and came out with the IRM-40a. they also had thier share of problems. hurth was aquired by ZF and that is what you see in the boats today PCM-40 and PCM_40a   
nowadays weight is another issue and at the time wakeboarding was not as popular and boat owners are trying to weigh the boats, opposite of making them lighter
The pcm in my eyes are delicate unlike the Borg Warner, parts pricing is the issue with the PCM, if you have a failure it takes more than $200.00 to get tham repaired

PCM labels the transmission for propriatary reasons (parts) they are actually a Hurth transmission and ZF marine bought Hurth.
Hurth did come up with a workable transmission which also includind a 1.23:1 down angle
At the time more and more aluminum case transmissions were evolving and the ski boat market was included. but someone near the top of the food chain made these decisions and the exact reason i dont know, but if i was to guess it was something to do with money

there is the 5000 series by Borg Warner which is all aluminum and Mastercraft uses the ZF 450a and 630v which are aluminum.
you'll be seeing more combinations in new boats as they evolve
they did try to re-invent the wheel with some good and with some bad. the thing about these transmissions is you can spin them either way for forward... full power which eliminates the need for right hand engines.It works graet all the way around for the engine manufacturers. it was unheard of to have 2 left hand engines in a boat, it was always a left and a right in twin screws.

gottaski, you got it f-n bulletproof, cheap to overhaul, simple to overhaul, parts available, need i say more
they use borg warners in everything, im doing a forklift trans right now and its a BW.
thge ZF line is great till you need parts and when you find the parts you will pay