Some Pinion Seal Help Please

[Zonaman]

Looks like my differential is leaking where the driveshaft connects. That's a pinion seal , I presume? I read up on it in my Haynes manual and it looks like something I can do but I have a few questions:

1. The procedure is slightly different if you have a semi-floating rear axel. How can you tell?
   
2. There's a small piece of duct tape between the u-bolt and the u-joint. What's up with that? Not some "cheapout instead of fix it right trick", I hope.

If it makes any difference,- it's a posi-traction diff, a 2-piece drivershaft, and it's been converted to a 700R4 trannie. See photos below and thnaks in advance!