I took a longer ride in my 68 Coronet. Out of sudden the ammeter went to full discharge and after awhile it went to full charge. Back home i changed the VR (mechanical) and put in a new 60 amp alternator. Multimeter across the batt terminals show 12,6 volts. With engine on it show around 13 volts. Now it gets confussing. Put in another VR (electrical) and voltmeter show between 12,6 - 12,8 with engine on. So no charging.
Put back in the mech. VR out of sudden ill get 15 Volt with engine on. So went to a buddy and get a brandnew elec. VR and again its not charging. Put back the mech VR (the one that puts out 15 Volt) and all it charged was between 13,2 - 13,6 Volts.

Did a field circuit resitance test (field@reg to +@bat) and the multimeter shows around 4 - 5 Volts (manual says shoould not exceed .55 volts).

Why isnt it charging with the electrical VR and why are the readings all over the place with the mechanical VR.

I should mention that i dropped the steering colum right before the drive to change the gearing box.

What to check next. Any help appreciated