There is very little relative lateral motion between the transmission and transfer case in that divorced arrangement that Dodge used. If you check the shaft alignment and shim the transfer case to get an on center configuration, I would THINK that 5" would be acceptable. I didn't run out and measure mine on my '72 W200 but doesn't 5" center to center on the U-joints only leave you about an inch of circular driveshaft?

"We live in a time when intelligent people are being silenced so that stupid people won't be offended".