2004r tranny or 7004r ?

[camaney]

Truck is runing great now I haven't go to 4th gear yet just drove it around the neighbourhood. It took me couple ajustments to the tv cable but now it seems shifts right. thanks all of you
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[nasqar]

Do you know what your mileage was before the tranny change? It would be kewl to see the difference after you get done tweaking it. Good luck bro!

[camaney]

It will seem like 12 to 15 can't wait to see the difference
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[gonzo6869]

Well??? have you had a chance to take it out on the highway yet? How are you likeing it?

[68GMCCustom]

I am also running a 200-4r...but haven't gotten to drive the trucks its in yet!

built for 500-600hp by a local shop w/owner/racer


looks a bit different now with headers but this is pretty close...

[camaney]

Ok so in the highway I was going about 70mph and rpm drop to 2000. Now, I'm not sure if the speed is right yet but judging by the other cars I will say is pretty close. Now I can hear my radio playing
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[capev86]

if you really want to get good gas mileage, stay under 60mph. a couple extra minutes on a long trip is worth it to save some gas, green and to be safe and legal. best mileage, even with good highway gearing is gonna be around 50mph in most modern cars. in a big truck with poor aerodynamics, the economy is only gonna suffer that much more as you start pushing lots of air and high speeds.

my dad's best mpg:

72 burb c10 305/350 3.73 - 15
84 burb c10 350/700 3.73 - 19
84 burb c10 406/700 3.73 - 17
87 burb c10 350/700 3.08 - 18
99 burb c10 350/4l60 3.42 - 22

my best mpg:
72 burb c20 307/3tree 4.57 - 11
72 burb c20 307/3tree 4.10 - 14

my impression: the q-jet is the best form of induction for power and economy short of fuel injection. all our trucks have run stock q-jets or tbi systems. 2wd will always get better mpg than a 4x4 with same drive train and gearing. it also cuts down on maintenance headaches and rides nicer. the 3.08 gear is too soft for a 5000lb truck and hurts mpg because it shift hunts around town and on hills.

the aerodynamics of the 90's trucks coupled with the "compromise" 3.42 gear makes for a capable truck with great mpg. truck is turning 1900rpm at 60mph. mileage on that first tank full included a fair bit of around town and also towing my 72 on a tow dolly a 1/2 hour away to get some work done by my favorite mechanic. a decent 5500 pound tow rating and 50 more hp than the engine than in the 87 and it handled the 6000 pound '71 holiday trav'ler 23 foot camper my family has owned since 1984. looking to get near 18mpg out of my 72 when i get my 66-69 borg warner equipped saginaw swapped in. although i know i will lose some when i swap in that 406sbc my dad had for a short while in his 84.

[passthebuck]

I like my 700r4 & I chose it because it was the popular choice at the time (94ish). Cant say anything against the 200 because I have never owned one.

[gonzo6869]

Originally Posted by camaney

Ok so in the highway I was going about 70mph and rpm drop to 2000. Now, I'm not sure if the speed is right yet but judging by the other cars I will say is pretty close. Now I can hear my radio playing
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I am happy you got everything done, now you can enjoy driving on the freeways and going on long trips