He has a 2007 so the dash must be pulled most of the way out to change the heater core
I assume you FOR SURE know the heater core is leaking and it's not something else, because it is a big project
There are several videos on whats involved, Google: Ford ranger heater core change video
Pretty much the same on 1995 and up Rangers, 1994 and earlier were WAY EASIER, as Alan said 1/2 hour tops
1995 and up is spec'ed as a 9 hour job but doesn't take that long, but for sure plan on 4 or 5 hours
Probably wouldn't be good if you have a hard time bending over or getting under the dash
There is no heavy lifting just awkward body angles
Just as a heads up, the Blend Door Actuator was a common failing on Fords, its the Temp Control for the cab
It's very easy to change with dash out, in fact you are suppose to pull the dash back to change it same as heated core
You may want to put in a new one just as general maintenance, but "if it ain't broken don't fix it" is your way, like it is mine, lol, then never mind
It's just a heads up