difference between 2600 and 2600i

tried searching but probably used wrong key words.Anyway,as the title says,is there a fundamental difference between these two? Specifically,the trannies. I have a low mile 91 2600i with a five speed,and some very high mile knees. Would like to get an automatic and keep on driving the truck. Thanks for any input. Steve

The 2600 is the Mitsubishi g54b carbed 2.6 whereas the 2600i is the Mazda g6 2.6 fuel infected. I don't believe the transmissions to be the same since the 2600 is a Mitsubishi motor. I've not researched much into what trans the Mitsubishi uses, but doubt that they are interchangeable between the different motors. If you have a 2600i you most likely will need a 2600i trans, either auto/manual, whichever you can find.