66 C10 w/250 Transmission Upgrade

[ADickson]

As the title suggests, I have a 66 c10 with an 250 inline 6. I intend to keep the stock motor but I want to upgrade the 3 on the tree to something that will permit interstate cruising speeds. It should be known that I'm less than mechanically inclined but rarely too skeert to try something new. I'd prefer manual (5sp?) but not opposed to automatic. What options do I have to, more or less, bolt in an upgrade with minimal fab work?

So far all the recommendations are to return my crate motor and get a 350 with an automatic transmission. Hilarious, but not helpful. Hoping someone here will have a solution.

I appreciate your time.

[Captainfab]

Welcome to the forum

Without changing the differential gears, you will need an overdrive trans. The simplest would be a T5 manual trans, but they are not that easy to find. The next manual trans would be the NV3500. That will require a hydraulic clutch conversion, which I happen to make and sell. For an automatic OD trans. I would recommend the 700R4, but properly connecting the TV cable to the I6 carb will be difficult unless someone makes a kit now that I am not aware of.

[ADickson]

I managed to find a couple T5s near me. Assuming they're still available, will the transmission mount need to be relocated and will the driveshaft need to be modified.

I'm not opposed to changing gears in the rear end. Would that change your recommendation for the T5?

[Captainfab]

You can leave the bellhousing crossmember along with the original bellhousing and just hang the T5 on the back of it. Yes you will have to have the driveshaft shortened. As long as your differential gears are 3.73's I would leave them alone. Changing differential gears is not something easily done for an inexperienced mechanic and is quite costly to have done professionally.

There is a member here that knows all there is to know about the T5's and what you will need. His user name is Lugnutz65. Here is one of his threads. His website links are in his sig line.

http://www.67-72chevytrucks.com/vboa...d.php?t=612147

[ADickson]

For poops and Snickers I checked Rock Auto for an 88 s10 T5. They have the pictured item. Here comes by first bit of ignorance. It says 4wd, I'm assuming it's "4wd compatible" since that's handled by a transfer case? (Maybe it is showing one, seriously ignorant here).

Another concern is that gear ratios very. That would make it difficult to match to the rear endif they can't provide the information specific to the purchase.

In you opinion, is this worth getting or have I got the wrong number?

I appreciate the resources you provided. That was a good read and answered a lot of questions.

[Captainfab]

You can NOT use a 4wd trans in a 2wd application. In a 4wd the transfer case bolts directly to the back of the trans.

[hank scorpio]

Tailhousing of a 2wd T5. The one pictured is drastically different to allow the transfer case to bolt on. *You might* be able to just swap the tailhousings and shift linkage but it could also be a different length output shaft. Probably cheaper and easier to stick with 2wd.