If it's similar to the 1994, it's pretty easy. The heater core sits on the passenger side inside the cab, and there will be two hoses running through the firewall. It should just be a simple matter of disconnecting the heater hoses, and removing whatever mounting bracket is holding it in place (screws or bolts). I replaced mine with a borrowed tool kit in about 10-15 minutes in a Suburban Lodge parking lot in Charlotte, NC back in 2000. I've always wanted to tell someone that story. Seriously, it won't be that difficult, just have a bucket to catch the little bit of antifreeze from the hoses.
It's one of the easiest cores to replace that I have encountered. Disconnect heater hoses at firewall. Probably doesn't matter about hose placement, but I always mark them just in case. To remove the fiber cover under dash, take a flatblade screwdriver and prise out the center pin of the expansion clips that hold it in place. There are four 5/16 head screws that hold the bottom/drain tray cover. Core will pull through the firewall and then down. You may have to silicone/glue or replace the foam seal strips on the new core. Before you install the core, check the distance between the inlet and outlet tubes to ensure they match the openings in the firewall. This saves time. It helps if you have someone on the outside to guide you when stabbing the tubes through the firewall. Replace bottom cover. You may have to hold one of the tubes when reinstalling the first hose to the core. Replace any lost coolant and check for leaks prior to reinstalling the fiber cover. If the cover seal is in good condition, any leak should drain through the firewall, otherwise it may leak inside cab. These days with parts from Mexico and others, it is not uncommon to get a new defective part.
Take it to a mechanic and say "will you fix the heater core?"
If your asking if it can be done without removing the transmission? NO.
No, the 2003 manual transmission will not fit a 1991 Ranger.
Motorcraft MERCON automatic transmission fluid is used in the 5 speed manual transmission according to the 1997 Ford Ranger owners manual
The manual transmission on a Ford Ranger should be changed on a regular basis. Fill the transmission with any good quality regular or synthetic transmission fluid.
Motorcraft MERCON automatic transmission fluid in the 5 speed manual transmission of a 2000 Ford Ranger in North America
Motorcraft MERCON ATF ( automatic transmission fluid ) is used in the 5 speed manual transmission of a 1999 Ford Ranger , according to the owners manual
According to Haynes Repair Manual #36071, 1993-2005 Ford Ranger pickups, all models: Manual transmission fluid type is MERCON automatic transmission fluid.
Manual transmission fluid is MERCON automatic transmission fluid.
The manual transmission doesn't have a dipstick , there will be a fill plug on the transmission
A better question is why would you want to put a ranger transmission on a mustang
Manual transmission fluid type ....... MERCON automatic transmission fluid. - Haynes Manual #36071 - 1993-2005 Ford Ranger Pick-ups.