1 piece driveshaft in 67 swb

[67chevyguy]

I checked the search and couldn't find my answer anywhere.

I want to switch to a one piece driveshaft in my 67 swb. I have a th400 and 12 bolt rear end. Does any one know the length of driveshaft I will need? Also, anybody know of a vehicle that will have a driveshaft that will be a direct swap into my truck?

I would measure mine but it's 600 km away and there is a lot more selection of places to find one here than the town where my truck is.

Thanks guys