looking for a 150 speedo for 67/68 prefer.

Here is a couple links for ATP 1st link shows both part#s and lengths.
http://www.showmetheparts.com/ATP/
Dads is 273/904 combo and 63" in length part# Y804.....rockauto website stated Y803 and 83" WRONG
Here is ATP home page..lotsa tranny parts/internals
http://www.atp-inc.com/