03 2WD Longbed Auto Aluminum Driveshaft?

[Thanks47]

My 03 2wd auto longbed ranger needs a new driveshaft and I'd like to find an aluminum one without breaking the bank. I just rebuilt the 8.8 diff with Ford brand 4.10 gears and bearings and a traclok. The oem steel driveshaft is pretty rusty and one of the u joint caps fits loose. I have a vibration that's pretty ruff from 60mph up that feels like a bad u joint. While the rearend was out I replaced the trans tail housing bushing and seal. The bushing was into the copper all around and I had some vibration at speed before the work. Now the vibration feels a bit sharper. Anyone know how many rpm the aluminum driveshafts can take in this length? I believe it will turn close to 3800 rpm at the speed cutout.
I'm willing to have an aluminum driveshaft shortened if I have to but I'm hoping to find a direct fit. Any advice is appreciated.

Just for the record I'm an old man, not a kid trying to hotrod it.