Spend a few minutes and get the measurements and call a place like Strange Engineering. I went by the specs off the internet minus an 1/8” based on my inexperience with measuring driveshaft slip yoke protrusion and had a local shop rebuild my driveshaft to that for a few hundred bucks… but I have +2“ leaf springs and now 6 degree shims correcting pinion angles. It turns out I was wrong on my length… Strange Engineering is now building a driveshaft that is 3/8” longer than what I originally had made (1/4” longer than factory spec). Oh, and this error on my part is costing well over $500 to make right using all new parts, cause I am chasing a driveline vibration above 50 mph… there are way too many factors to guess a number… including what’s the correct slip yoke protrusion. I ended up at 1.25” with my first attempt, which industry standard is 3/4” to 1” max… don’t guess, measure what you have…
