first off I'm new to this site. I have a 98 F 150 with a 4.6. I need to know if I should upgrade to a 5.4 or switch out my axles for 308 to 355. I have a mechanical background so it's not going to be hard for me. I tow a big boat and the truck seems like it need a little help. also I forgot to mention it is a manual transmission. on the whole way it seems to do fine it's just on the low end. and on the highway I can't go faster than 65 hauling something like that cause that's all the truck will do. Any suggestions would be nice thank you

 

Personally I'd do both if possible. If you're only going to do one, I'd regear. 3.08's really tall for towing.

 

It would be cheaper and less time consuming selling what you have and purchasing a heavier half , - same year same/close in price. Like say, -a 7700 model. The 7700 will have what you need in a half ton, right out of the gate. Just keep up on maintenance and she'll take care of yuh..

 

X2.
You'd have thousands into a swap where you could just pick up a more capable vehicle.
Also, that 5spd wouldn't be too happy behind the 5.4.

 

Sure it would... for a little while

 

That is true but there is a good pick and pull close to my house. After all said and done I could buy a 5.4 and diffs for around $500.

 

Both will be best in the long run

 

Your going to need allot more than just the diffs. Refer to post #5...trust me..

 

Send me some.

 

If it was me, personally I would do the follow.

Throw a couple twin turbos on the 4.6 upgrade to a T56 tranny, change to 3.73's. Then you can pull a fiberglass boat with no problem.