1994 4.0 Engine Replacement Options
 

I have a 1994 Ranger 4x4 4.0 5 speed manual. The motor has 342,000 miles and is in constant need of oil and coolant added. Intermittent knocking noises from the motor etc. Clearly its time is limited and I'm trying to decide what I'd like to do. This truck has been my daily driver for 14 years, I love it and would like to have the motor rebuilt or replace the motor with something else and it continue to be my daily driver.

What do I need to know going into this? Am I best off finding a Reman motor? If so what's some recommended brands? If I pull the motor is it potentially cost effective to take it somewhere and have it rebuilt as opposed to finding another motor? Should I consider V8s that could still get decent gas mileage etc compared to the 4.0 in it? Any and all information/opinions/recommendations is welcomed!

You need to know costs going into this.
Do you have a budget? If so, what kind of moo-lah do you have set aside for this?
If you can pull and reinstall a motor, you're greatly ahead.
Often you hear, "Get a junkyard motor", but sometimes you don't know what you're getting. Any GOOD yards near you?
A yard near me is an engine clearing house (last pull before the crusher, I suppose). Remember, your OHV engine was replaced with the SOHC 20+ years ago so you'd be looking for a ridiculously young engine or one which had been rebuilt.
All that uncertainty (time & money) leads one to having yours rebuilt.

I've read about "national companies'" engines being both good and bad. Any LOCAL rebuilders near you? Ask at sharp looking garages.
Not every ancient engine is repairable (bearing surfaces good enough to have replacement bearings installed? Can the heads accept new valve guides if needed? Has the engine been treated to a hot lunch?).

If you're at all a hands on guy you know that swapping in a V8 is a bigger deal than just the schematics. The engine management, weight change in the front suspension, clearances.
You don't sound like a car star with lotsa money. Fix your engine or replace it. Forget the V8 idea.

And remember: When engine work costs $2,000 - $4,000 stupid people say, "The truck ain't worth it".
Smart people say, "A replacement truck is $17,000 - $78,450 so I'll fix mine".
Obviously, if your vehicle is a mass of rusty corn flakes it's time to say good-bye.

I have the ability to pull my engine and replace it with another or put my rebuilt one back in. I made the v8 comment more in jest to draw any and all opinions. My initial plan has always been another 4.0 (either mine rebuilt or a new reman) with hopes that I can get another few 100k out of the new/rebuilt motor. I intend the truck to stay a daily driver after updated so I’m looking for practicality. I truthfully have not considered an actual budget, but have known it’ll be at least a few grand obviously. That’s way cheaper than finding an equivalent daily driver that I will have no history with, so in hopes I can lower some costs by doing my own engine pulling/replacing, I’m not too focused on a budget because this is an investment on what I intend to be another decade+ of being my daily driver.

Since you're focused a little bit on this, do us a favor please.
Gather some intel and get back to this thread.
If nothing else, it'd be interesting to hear what a rebuild costs in your neck of the woods.
Post a pic or two of this '94.