Which fan clutch should I use ?

8ED03F5C-1B71-458E-942A-F7F2DD6F081C.jpeg A friend had these parts laying around. My 79 d100 (318) has the direct drive fan. I wanted to switch to a clutch fan. He gave me these. The right fan and clutch is off of an 86 w250 318. The left clutch he couldn’t remember. Any idea what the differences are (other than diameter) and which one would be best to use?
Thanks