Another oil cooler question

[Uitenhage]

I have reported earlier that one of my current projects is the restoration of an 750 J , which will be used as an track bike until the 'J' race bike project is complete. In my quest to source the appropriate oil cooler for the 'J', I came across three different ones, posing the question of "how many rows did the original 'J' oil cooler have?" The distance from the top mounting hole to the bottom frame support on the 'J' frame is 235 mm, and 2 of the three oil coolers I have are short of the bottom frame support by around 20 mm, give or take.

The first pic is a substantially bent curved cooler, possibly later 750 or 1100, the fact that it is bent being the reason it is shy of the bottom frame supports. The second pic seems to be a presling cooler as I had to make a adapter to attach it, and the third one seems to be a older 1100 sling?

 

[dupersunc]

The Curved L,M 750 and F,G,H oil coolers are all 15-20mm shorter than the J,K oil coolers, so you'll need to make some adaptor brackets to fit them.

[Uitenhage]

Thank you! Now it is starting to make sense. Any idea how many rows a std 750 J cooler suppose to have then?