Drive shaft Length Long bed Chevy

[CBakes]

   Hey Guys, Curious to see if anyone knows the standard length of  a long bed regular cab early to mid 80's Chevy pick up rear drive shaft. This could be just the ear to ear length without the yoke. Secondly, has anyone shortened one of these before to use in a mid 80's K5? I am about to have my stock rear drive lengthened and though maybe just have a 3/4 ton or 1 ton shaft shortened.... Are they any more durable? Any input would help. My Blazer has 8" soft ride sky jacker system and drive angle is just too much. Thanks.               Chris