K20 Suburban Transmission Issue

[ch2000]

I recently purchased a decent shape Suburban K20 but I have run into a little issue that I was hoping you guys might be able to help me with. I have been away from Chevy 4x4s for sometime so I am not sure on this one.

I had to have the truck towed last week due to a little issue and after the truck was towed (Flatbed) the truck will roll while in park. The transfer case was put into neutral as it is still a full time 4x4 system by the tow truck driver and then loaded. Once it was dropped off to my house the transfer case was put back into 4-HI LOC but when I put the truck in park it will still roll. I tried putting the transfer case in different ranges but when I put it in park it will roll. I can drive it with no problem forward and reverse.

Any input would be appreciated, also the trans is a TH400.....