wow... this is mostly a yota sight you know that right lol...... well anyway i know a bit about rangers and mazdas and i can tell yea for #1 - the 2.6 and the 2.9 are COMPLETELY different engines... absolutely nothing will interchange...
#2 - The 2.9 is.. for the most part.. Crap also.. they are like 3.0 yotas... some run good, some dont, but they all will have problems eventually...
if you got the engine, drivetrain, wiring, all that stuff (pretty much a donor truck) then go for it. But if not, you would be alot batter off going to maybe a Mitsubishi 3.0 v6...IIRC you can re use the factory transmission with a differant bellhousing...
or for that matter you could also do a ford 3.0 or 4.0 swap (looking at the same parts as a 2.9 with alot better aftermarket and parts availability)
on a side note. If you located around me (Oregon coast) i know someone who will buy your dieing engine
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