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Pretty low miles so this Ranger sat for long periods or was driven very short distances, neither of which is good for the truck over all.
3.0l Vulcan engine was used by Ford from 1986 to 2008 and is a very reliable engine.
Ranger got this engine in 1991 and had it until 2008 when Vulcan model was discontinued
1986 to 1994 3.0l used a distributor with TFI ignition system, 1995 and up were distributorless
The TFI module on the distributor did wear out, cutting out when warmed up or hard restart when engine was warm were common signs of failing TFI module
1992 Ford vehicles used OBD1 and the EEC-IV computer, so OBD2 code readers won't work with it, but you can get codes by using a jumper wire and reading the flashing Check Engine Light in the dash, pretty easy to do this.
1995 and up Rangers had OBD2 and EEC-V computers
Change the coolant if it doesn't look fresh, changing every 2 years was spec, not doing this will cause electrolysis because of the mixed metal in the cooling system, i.e. cast iron heads and block with aluminum intake
All pickups seem to suffer from rusted out rear spring hangers
You will have the M5OD-R1(M5R1) 5-speed manual in a 1992 3.0l Ranger, these were very very reliable, the older 5-speeds used in Rangers did have issues, but all that ended with the M5OD-R1, it was used in Rangers until 2012, last model year
M5R1 does have integrated bell housing, doesn't detach, so M5R1 for a 3.0l engine will not fit a 2.3l or 4.0l engine and visa versa, parts inside are M5R1 but the case is engine specific
M5OD uses ATF..............yes, automatic transmission fluid, NOT gear oil
O2 sensors use a chemical reaction to work, just like a car battery, so they do just wear out like a battery, 100k miles is recommended replacement time but I often do 150k before MPG starts to drop, O2s wear out RICH, so costs you money as they get too old.