Driveshaft issues

Background: New member & first post, please forgive my missteps. Have read many Driveshaft-CV-Guibo-CSB articles on this forum and many others, my apologies if missed something. Did my best to follow those directions and advice.

Symptoms: Between 35-40mph vibration in floor/seat and can feel in shifter, vibration seems to follow speed in that range, not felt much outside that range, felt on accel but seems more prevalent on decel/coast (with or without clutch engaged & engine at idle)

Work performed: Marked & removed driveshaft, replaced CSB-Guibo-Centering Bush-All hardware. Separating shaft sections was very difficult. Carefully cutoff CSB (hit nothing but bearing/bracket). Then, used opposed cold chisels (on opposite sides of shaft) to create a wedge and force sections apart [in hindsight maybe not best idea]. Reassembled and reinstalled.

New Symptoms: Still have vibration in floor/seat and can feel in shifter knob; the vibration follows speed and may be more intense than before, but now is Always present

Questions: Could it be the CV? Is it out of balance (misaligned reassembly)? Did I potentially bend the splined section during disassembly? Any other thoughts?

Sorry for the length, but wanted to get the pertinent details in here. Thanks in advance for any help !

We've had a member here that had a driveshaft go bad, so it's not unheard of to have to get a new/used driveshaft.