Found this on Alliexpress. Hope it is helpful.
Check it out! $47.48 28%OFF | NCR60E 4L60E Transmission Wire Harness Adapter Stand Alone Controller Manual Shift Conversion NCR 60E-T 1993-2008
https://a.aliexpress.com/_ms4kUfY
Also still looking for a K3500 crew prop shaft frame cross member.