Here you go some help with fitment ... I like the idea its the TCC
Transmission Length
Case to ext. housing Overall length Bellhousing to mount
Powerglide (short tail) 15 ¼ 24 ¼ 19 ½
Powerglide (long tail) 15 ¼ 27 ½ 20 ½
THM 200, 200C (the 3 speed) 27 5/8 27 5/8 20 1/8
THM 250 21 5/8 27 5/8 20 3/8
THM 350, 350C (short tail) 21 5/8 27 5/8 20 3/8
THM 350, 350C (long tail) 21 5/8 30 5/8 20 3/8
THM 400 (short tail) 24 3/8 28 ¼ 26 ¾
THM 400 (long tail) 24 3/8 34 28
200R4 27 ¾ 27 ¾ 26 7/8
700R4, 4L60, 4L60E 23 3/8 30 ¾ 22 3/8
4L80-E ? 31.5 30.38