Tremec swap - looking for driveshaft donor to have shortened - 31 spline spicer 1330

[Chuck78]

I'm looking to install a Tremec 3550 5 speed trans (older version of the TKO) into my 62 GMC panel truck with the X-frame. I was wondering what options I had for driveshaft donors, as I would like to keep my original driveshaft intact in case I ever for some unforseen problem need to swap back to the SM318?

the Tremec takes the 31 spline spicer 1330 yoke, which I believe is the F*@d C6 yoke. I was wondering if anyone had any ideas on what donor vehicles I could look to in order to find either another shaft of the proper length to either use as is or get shortened (surely I can't find the exact length stock) with the 1330 U-joints on both ends, or one that takes my stock U-joints for the 1 piece driveshaft on both ends.

The shop here can make me a new shaft with whatever ends I want for $250, or shorten an existing shaft for $65. If I had one shortened, I'd probably try to avoid a half and half "conversion" u-joint and have them do one end with the spicer 1330 joint and the other end with the stock dana 44 rear end joint at an added cost. Hoping to save $125 or so and just find a shaft at the junkyard that will work. I need assistance at least spotting out the correct shaft in a pile of driveshafts, or else knowing what donor vehicles I could find a steel shaft to shorten or an aluminum shaft of the correct length.

I wish there was a chart somewhere of driveshaft applications/lengths/u-joints!

Thanks guys.