So I have been toying with the idea of manual swapping my Dakota. I've read through the write up on the T56 swap (very helpful) but I'd like to try to get a Tremec Magnum to work instead. I think I am close to working out all the parts but I've come across some things that I just can't figure out. From what I have seen on here, plenty of people have done T56s or TKOs so I was hoping for some input.

Firstly, there are two Magnum options, one for GM and one for Ford. Both similar except for the input shaft lengths. The input shaft length from the face of the transmission case to the very tip on the GM is 6.46 inches versus the Ford at 5.64 inches. I've also seen there are two different Quick Time bellhousings for the T56 available, part numbers RM-8074 for the GM version and RM-6076 for the Ford. Both have bolt patterns for T56 / Magnum transmissions to mount to small block mopars. The main difference in the two is height (distance from back of engine to transmission), GM version is 6.465 inch and the Ford is 5.525 inch. Now what is confusing me is that say if I use the GM Magnum transmission and the GM bellhousing, the dimensions work out so that the input shaft of 6.46 inches - the height of the bellhousing of 6.465 inches = -.005 inches, essentially the end of the input shaft won't be sitting into the pilot bearing. For the Ford: 5.64 - 5.525 = .115 inches, in the pilot bearing but certainly not enough, should be .75 to 1 inches, correct? To get the numbers to work out, I would have to use the GM transmission with the Ford bellhousing: 6.46 - 5.525 = .935 inches. This seems strange, I would think that GM would go with GM and Ford with Ford, but considering that the bellhousings were designed for the T56, maybe the input shaft of a T56 is different than the Magnums. I have yet to be able to find a consistent number for the length of the input shaft on a T56. I know that there are Viper, GM, and Ford versions of the T56 but since they've been made for so long, I'm afraid there could be many combinations of input shaft lengths so I can't confirm.

Secondly, just to make sure, the bolt pattern to the bellhousing for a GM T56 and a Ford T56 are the same, correct? This would mean that the GM and Ford Magnums are also the same.

Lastly, gear ratios, the Tremec Magnum has two options. The narrow gear set has a 1st gear ratio of 2.66 and a 6th gear of .63, the wide gear set has a 1st gear ratio of 2.97 and a 6th gear of .50. Compared to the 46RE's 2.45 1st gear and .69 4th gear, it seems like the narrow gear set is pretty similar just with two more gears. One of my goals to have low rpm highway speeds which makes the wide gear set seem better, but I'm worried that the 1st gear will be too short. I could fix that by swapping out the rear gear from the stock 3.92 to something smaller, but that may make 6th gear so tall that its almost unusable. Similarly, if I swapped to smaller rear gears while using the narrow gear transmission, I could have a tall highway gear but too tall of a 1st gear. Other considerations are that I don't plan on drag racing, mainly want good backroads street driving and maybe some autocross. So to those who have swapped to a manual (and I'm certainly willing to hear from those who haven't swapped but want to weigh in), what are your opinions? What transmission, gear sets, and rear gears are you running and how do you like it? Should I go with the narrow or wide gear set?

Any other thoughts or comments on a Magnum swap would be appreciated as well, thanks.