Well Im taking the leap and while my engine is getting a leak down test soon, Ive bought a pre-1992 700R-4 overdrive auto. for good ole Thunder.
The guy that builds them around here is 74 years old, has been building trannys for guys all over the area for 35 years. His nephew is a good friend and parts manager for 26 years locally.
It will have a torque lock out when it shifts into overdrive only. It comes with the TVI cable and I will need to get my driveshaft shortened, $60. Not bad.
Depending on what he finds inside the tranny when he tears into it, my 'out the door' price will be under $650 total from the tranny builder. Then, plus the driveshaft and installation cost by my mechanic guru thats doing the leak down work.
The info. Ive read on the 700R seems to make it the best route for me now. With my 3.08's in back and 26" tires, Im told to expect about 1800rpm at 65mph. Around 2000 rpm at 70mph. My mileage should go up from 20 to close to 27mpg on our trip next summer out east somewhere. Now I can keep up with JimM too :) With my TH350, Im cranking 2500rpm now at about 62mpg so this will be a big difference to me. I cant wait but they are forcasting snow here on Wed. night and Thur. yuck :(

Congratulations! That out the door price includes the install? That seems really good for all the work and parts that are going to go into it. Does your tranny guy ship to CA? :) I'm casually considering a 700R4 for my 350 stroker; now that the new top end is in, my gas mileage plummetted.
Too bad about the snow, good luck!

well, a big congrats, Jim, and welcome to the modern world!!
Now thunder can be pro-touring, too!

So where are we going next year?
Carlisle could be fun, but it was a blast doing our own show last year, too.

And this does mean I won't hear about any imaginary speed limiting vibrations, right?

JimM, wheres' Carlisle?

I clarified the text in my first post, that $650 is NOT for installation too, just the tranny out of the tranny shop door to be installed by my mechanic. :)
Carlisle is in Pennsylvania, all summer there are old car gatherings there.
Pro Touring? Wow I didnt think of me in that class.
Im still up for a TC gathering in N. Indiana or N. Ohio so HwyStarJoe can join us. :)

If it vibrates after all this, Im getting new wheels too. :) Ralleys of course.

Congrats Jim, you'll love the OD... Save yourself some OD headaches and do a rear gear change to something like 355's or possibly 373's. Your 308's when in overdrive won't be able to over come the the weight and rolling resistance of your car unless you have a real torque monster making power as low as 1500rpm. It might be fine on a flat road doing 70mph but the first hill you roll into it will be back to 3rd and 1:1. Same as with around town driving. I went to 342's from 373's and even with all the lowend stump puller power of the stroker I can't just put it in drive and leave it alone. When I had the 373's it was enough gear to not lug at 45 mph when rolling into it.

It's a cool upgrade but there is a balance of low rpm torque and rear gearing to get the most of your od trans. On that note since your having the engine refreshed you might look into what it would take to make more low end power...

Oh my best mpg came with 373's @ exactly 60mph for over 100 miles, I got 24mpg. After switching to 342's I have gotten 21 and 22 mpg but at about 70mph. :thumbsup:

Ouch Dennis, think Im made of money like you? ;) Those 3.08's are only 2 years old and thinking about your gear comments made me think... most of our driving is highway driving to and from events etc. If we did another mountain climb thru the rockies, that stretch I could handle in just 3rd gear easily and then back to O.D. on the flat roads. Im hoping not to get in any deeper than oil seals and pan gasket and the tranny itself if I can. I can always change the rear gears down the road as another project if the O.D. isnt giving me what I want too. Id rather get 27mpg at 70 and downshift to 3rd on steep hills, than change rear gears again but I certainly see you logic to it. There sure are alot of things that factor into one desired result. The old snowball comes to mind :) Now if Al would triple our pay in here .... hmmmm? :beers:

I'd go with a Shift Works conversion for your shifter and I'll also recommend the BTO TV setup. I used the regular TV cable for awhile and can tell you the BTO setup is well worth the money. Also a trans cooler and trans temp gauge aint a bad idea. Oh, and first gear in these things is a hoot. Enjoy.

With the original manifold and q-jet, an original TV cable from a V8 700r4 full size q-jet car built in the 80's will do the job and maintain a stock appearance.

Ditto what Robert said on the shifter.

get a bto crossmember.

I think the 3.08's will be OK. She'll hunt from 4rth to 3rd some, but it shouldn't be objectionable.

Ok, shifter kit is $85 but the crossmember is $175 yikes, I have a write up on a guy from www.smokeEMup.com that did the conversion and used the TH350 crossmember, just moved it back and drilled new holes in the front sub frame, using original back bolts as the front bolts for the 700R4 and drilled the sub frame to match the crossmember back bolts. My mechanic thinks that will work but if not he can temporarily get it in there and I can order the BTO crossmember and install that myself later this winter if need be.
I really appreciate the feed back guys, my appointment for the leak down test is Oct. 18th at 8am. Snow is starting to fall here now :( I just finished blowing leaves, time for a :beers:

I forgot about the crossmember. I used the BTO but it was only $125 about 5 years ago. Inflation. :sad:

The BTO TV is more of a performance piece.

Get your trans guy to put in the right speedo gear so you wont have to mess with that.

Also, you might want to consider a little bit more than a stock stall. Say 1800+ there abouts. It can really wake up even a stock motor. I think there's a stock Corvette converter in that range maybe someone has the part #.