Tranny clutch or transfer case problem 86 ford f250

So I have a 86 ford f250 with the 460 4x4 starts runs
beautifully but ran into some issues I'm unsure about I got
rodded her last year and all the sudden it just wouldnt got
so she starts but doesn't go I drop it into gear without any
problems but wont go so I went and bought another t18
transmission put her in and put her together and same
thing so i disconnected the drive shafts and put her in gear
and the joint that connects to the driveshaft moves but I
can grab it with my hand and stop it while in gear so I
thought maybe the transfer case so I took it off and
checked again but at the input shaft that goes into the
transfer case same thing I can stop it while in gear so I'm
really confused if anyone could help me narrow down my
problem I'd greatly appreciate it