Why am I getting a weird measurement for a driveshaft?

Hey, guys.
I just installed my new rear axle, Hotchkis lowering springs, shocks, etc...and I'm measuring up for a new driveshaft.

So it's a Magnum 5.9 bolted to an A904 in a Dart Sport. The rear end is a Moser 8.75" with their stamped housing with a 1350 yoke. I called Moser and the guy I talked to was fairly sure that the hosing wouldn't make a difference from the stock location.

This forum shows people with the A904/8.75" combo getting 49" give or take shafts...I got just under 53"!

The measurements were done with the car off the ground but with jackstands under the axle at the rear and jackstands at the front holding the car just about level. I measured from the flat/farthest forward point on the yoke to the seal...

Any ideas?