The 617 into the Toyota Tacoma is a mighty tight fit. Radiater needs to be moved, and I think the body might need to be lifted a little for the trans to clear, if you stay with the Mercedes auto. If you change to a manuel trans be aware that the flywheel is balanced for each engine, and if you change it(which you will need to for a manuel trans) the new one needs to balanced for your engine.

I am starting on a 616(240d) conversion into a Toyota pickup. This should fit much better. Oil pan may still need some reworking. But at least it has a manuel transmission. I plan to add a turbo to it. Yes I have read most all the posts about adding a turbo.

You may want to look at the Dodge Dakota. I don't think you will get anywhere near 35-40 mpg though, more like 25 or so. The 617 will fit much better. I did look at this truck myself, and ruled it out as being to big, and likely to be poor milage. i do have a full size Dodge, of course with the Cummins, so for me a mini truck with really good milage suits my needs better. This is why the 616 with manuel trans into the Toyota.