aluminum? DOM steel? c/m? carbon fiber? and why?

C/M. you can run less diameter than the others and the terminal velocity is way past what you and I might get into. AND... the price is right.

Steel, the weight saving of CF, AL is really small and very little inertia due to small diameter.

just ordered an aluminum shaft for my impending 904 project. About anything I've ordered/bought/changed on the car since getting it from my dad has leaned toward the lighter..... except the R3 and W8s.

I depends on the use of the car. If it is a heads up car, or in anything where the lowest possible ET matters, you need to save every ounce you can. An aluminum or CF shaft is a good way to do that.
If lowest ET is not your goal and low cost is important, steel is a durable, budget friendly way to go. According to Monte Smith, CF is safest because it disintegrates when it breaks, minimizing damage to the car and risk to the driver.

Chrome Moly

J Body, care to share who you ordered your shaft from? and the quoted price?

i like big and dumb. mine is 3.5 dom. built by mark williams in ventura cali (no relation, i don't think). he dared me to hurt it. so far this monster is laughing at my pathetic attempts. big and dumb. with big and dumb solid 1350 u joints.

$660 delivered with 904 1350 slip yoke. 3.5" Inland Empire Driveline

https://www.iedls.com/?a=Custom_Aluminum_Driveshafts#Home

Jay did you do exhaustive research on the shock loading ability of the aluminum vs steel shaft and the weight difference, or did you buy it because it was shiny?

I went with Inland as that's the direction I was led when I was having vibration issues with the Mirada. The faster we went, the more frequent we would break tailshaft housings. That driveshaft had been "checked" at two different shops and deemed "ok". Although I had tailshafts stacked like cord wood, I was worried my supply would end. The piece I got from Inland stopped the breakage. I'm sure there are many other "performance" oriented driveline shops that could have achieved this also... just not the one that built our steel one

Strength in the aluminum shaft is usually met with larger diameter, but for the length the 3.5 diameter should hold anything I throw at it (and Inland agreed). I've also been "trying" to go the lighter route on parts within reason when I can. Lb here, lb there = LBS

If it isn't shiny are you asking if you can polish my shaft?

Jay polishing your shaft might be a good idea to prevent stress risers from forming. But should probably be done in the privacy of your own garage.

50 years ago, someone much smarter than me said "no race car is ever finished, until you build the next one".
What does that mean: what you don't spend for the unobtanium driveshaft will buy that fuel pump you'll need next month.

think I followed that analogy my first time with the Mirada and ended up buying so many parts twice that car could have been in the 8's if I just spent the right money the first time

Somebody really smart once told me "when you buy the best, it only hurts once".

I went with the Mark Williams 3.5" Chromoly with 1350 U-Joints, and the matching trans slip yoke. The rear end is the Strange S60 with 1350 yoke.