What you have there that you un-bolted is the drive line.  It will come apart, just give it a smack with a hammer.  The PTO adapter is bolted to the flywheel and your  drive line bolts to it (yours is still on the motor).  Service wise, all there is to do is make sure the u joints are in good condition and lubed.  The way to determine exactly what size you have is to measure them.  This will tell you if they're a 1310 or a 1350 size joint.  I'll attach a chart so you can see what I'm referring to.  Bigger is better.  A relatively stock motor, say under 500hp a 1310 will be fine.  If you start building some real power, you would probably want to go with the bigger joints.

http://driveshaftspecialist.com/HTML%20Measure/UJ%20ID%20Guide.html

I would replace the joints while its apart just because... they usually are loaded new but a light amount till you feel some tension or see a bit of weep out cap. I use Lucas red n tacky.

Will my 1310 setup accept a 1350 joint or do I need a different carrier for the bigger joint?