Ok, so I've been doing a bunch of research and pm'ing several people on here, and thank you to those I have for being knowledgeable and putting up with all my questions. I have pretty much gathered that the 351 and E4OD get roughly 14 or 15 unloaded highway and around 8 towing. I'm wondering what kind of mileage the 300 with M5OD gets, and how that would do for towing? Also, which drivetrain is more likely going to last longer? Thanks in advance!!

 

I'm sure the mpg of the 300 won't be much better at all, but just curious. The main point is which engine/trans combo will last longer.

 

The 300/M5OD can produce 20+ MPG unloaded highway with 3.08 gears, a bit less with 3.55s but...

If you're going to tow, do not get the M5OD. It is a very light duty transmission and trucks equipped with it are only rated to tow 2000 lbs.

 

My jeep has 3.07s in it. I know with that, it sucks on the hills. How would the 3.08s on the 300 do, especially for towing? Thats good to know about the M5OD. isn't there another manual, the T18? How would that be? How does the E4OD do for towing? Would it be difficult to install a trans cooler on it?

 

Ford discontinued the T-18 sometime in the mid to late 70s. The similar NP435 was used through the mid 80s. The T19 which has a synchro 1st but is otherwise very like the T19 was used in F250-350s through the mid 80s as well.

The 95-96 E4OD is a very good transmission for towing, the earlier years had some issues. The upgrades can be retrofitted to the earlier years but it is an expensive tranny to rebuild.

All automatic trannies have a cooler and all are equally easy to add an auxiliary cooler to.

 

What kind of issues did the earlier years, say 94, have?

 

Here we go again... Mine is an 88 and has a T18. I think they also used it in 3/4 and 1 ton trucks. Pretty much bullet proof. I think if your looking to to heavy loads the 3/4 ton will do the trick. I'm not towing heavy loads and just wanting light to moderate 4 wheeling, so the 1/2 ton 300 six was the ticket. It has 355 gears. Around town mileage blows. Haven't taken it on a long highway trip yet.

 

The heaviest thing I'd be towing would be roughly 6000 lbs (my jeep and trailer). Typically though, I'd only be towing my boat which probably weights 1500-2000 including trailer.

 

My 95 with the M5OD is rated for 3700 lbs towing and I tow a 4500 lb 5th wheeler once in awhile for a total of about 300 miles a year. I don't use 5th gear unless the vacuum is higher than 11" and I only maintain speed I don't try to accelerate. The ZF is much stronger if you plan to haul over 4000 lbs. I liked the T-19 and NP 435 but they don't have OD.
SBF engine longevity is more about use and maintenance rather than type. I have run two 300s past 200k and a 302. Many users with 351s and have easily past 200k. All of these were DD with some hauling and had the oil changed every 5k and using Motorcraft parts when needed. The 300 seems to keep going forever and with 5 speeds are OK but the ones I have driven with autos were pretty slow. My M5ODs have shifted well without any problems except for the oil plugs on the shifter rails.
A snowplow/landscaping contractor friend loved the 300/C6 combo calling it the best powertrain for commercial use ever. He normally kept his trucks for 5 years but kept those a full ten before the rust got too bad.
regards
rikard