I am sure I am out of turn - but - I am pretty sure Marshall is no longer selling these carbs.
I will add that I had one on my 40 and it did not work at all then Marshall replaced it quickly and I had no further issues.
I am not sure but I THINK they can be found on ebay and possibly amazon at this point. The down side is that Marshall made sure his carbs had the correct throttle linkage for your application. I replaced an ornery Weber and was quite please.
It may be this one:
1969-1987 Toyota Land Cruiser 2F 4230CC FJ40. Interchange Part Number:21100-61012, 21100 61012, 2110061012, 21100-61050, 21100 61050, 2110061050. This tractor part replaces. 100% tested for reliability and performance.
www.ebay.com