I have a 91 f350 dually 2wd crew cab with the e40d transmission i would like to change to a manual trans i know the basic of what i need i was just wondering what manual trans would be better if there is more than one option. Also if pedal assy and column out of a f150-250 would be the same or not. Is there maybe a 6 speed trans that would work do not want to go through the troble unless i am putting a 5 speed or better in. Thanks for the help in advance

Trans, mount, flywheel, slave cylinder, pedal assy.

Easiest trans would be the ZF5 as its what was available in the trucks. IIRC, so long as the pedal assembly is for a hydraulic system it's an easy swap, holes should all be there. Column is a swap from a manual equipped truck.

No six speed.

Pretty sure the only pedal assembly you can get in the 87-91 trucks will be for hydraulic...

You are slightly limited if you want the speedo to still work. As of 92, there is no hole for the speedo to hook up to, they read off of the rear axle ABS tone ring.So you have the window of pretty much 87-91 to get a transmission form. You will also want the removable transmission hump from the manual transmission truck floor pan as well. The front driveshaft will also be a little different, as the u-joint bolts in to the output yoke on the manual, while you have a slip yoke on the auto, and is likely a little bit different length.

You will also need the computer from the manual trans truck.
I did the swap, and the truck ran like crap until I changed the computer

doing the swap is pretty simple and like charlie said swap the computer as well.. but also fyi.. ford did have a towing rating difference between auto and manuals. was a 200-400 lbs less with the manual than the autos. not very much but just a little tidbit there for you.

Thanks for all the help i am looking at a 90 f250 regular cab long bed for all the parts i guess the only thing i will need to search for is a drive shaft or get one made