I'm wondering were I can find information or sources for an overdrive unit that is basically a bolt-on scenario. I'm dealing with a 1977 f250 LWB 4x4.

 

Gear Venders is probably one of the most well known
I’m sure they would have something, they are not cheap, but very dependable building units that handle 1000+ hp.
I checked on one for my 2wd C6 , it was $3500.

 

RP: Thanks for the reply. I looked at Gear Venders yesterday and thought the price was too high.
$3,500 is nearly 1,000 gallons of gas. That translates into a lot of miles to drive in order to recoup
the investment.
I have a '67 F100 with a T85 BW transmission with overdrive. That is the sort of thing I'm looking
for on this '77.

 

Yes it is high and you still have to get a drive shaft
But in contrast transmission shop wanted $1800. to rebuild a of transmission for me if I found a used one in good shape
My c6 was 900.00
Good luck

 

It’s not my truck, I’m just working on it. It’s a 351M and should be a C6
Automatic.

 

Today I'm going to compression test the motor. It starts somewhat lumpy, like it has a cam that was put into it.
When she got it a little over a year ago, it was a 2 bbl. I told her that the carb needed to be worked on. She took it
to a shop and they said that the carb was all screwed up and needed to be rebuilt. They did that and it still didn't
run right. Then she took it to another shop near where she lives and they recommended a 4 bbl. She had that put
on and was somewhat initially happy, but it still didn't run right. Then she took it to a relative who is a mechanic
and they did whatever it was that they did, I'm not sure what that was. So, the few times that she has driven it
she is shocked at the poor gas mileage. I'm going to look at what I can do on the engine and see if there is a transmission
that will help. I'm also going to see what reared gears she has. She doesn't need 4:11s. But, considering it's
a 4x4, I'm not sure what can be done.

Now, she has asked me to look at it. She thinks I'm a guru or something because I own a great running 1941 FH
Pickup and a great running 1967 F100 with an original 352 ci engine.

Any help would be appreciated.

 

So, here are the not good compression readings that I got yesterday.
#1 125 psi #2 100 psi #3 80 psi #4 130 psi.
#5 80 psi #6 90 psi, but it bled down to 0 psi #7 0 psi #8 130 psi.

Based on those numbers I have a valve issue on #3. On #s 5, 6, & 7 I believe I have a bad head gasket issue with a possible valve problem.
There was no change when I put oil in the cylinders.
The best case scenario is to pull the heads and do a complete valve job.

Any ideas to the contrary?

 

It sounds like you're on the right track, but in case you're not aware of it I will point out the potential block cracking problem with early '77 M blocks cast in Michigan. Unrelated to your issue, but check for cracks in the lifter gallery while you're in there.

 

Oldiesask: I'll have to find the casting marks to determine when the block was cast. Where should I look?
The thing about it is the engine runs really well. There are no hiccups throughout the rpm range.
If there are any block cracks, then I'd probably get a 400 crate motor. I'd prefer a 400 for the better
torque numbers. The trucks is used to haul horses.

 

I have a good 400 for 500 bucks, but it's a long drive to get it, on paper, a 400 is only 5 HP more, but they wake up a lot better with that 4V. Next to the oil pressure switch is a casting mark, MCC for Michigan, CF for Cleveland, I can't recall where the date stamp is, but I think Fordification has a page on that. The flaw was corrected at the end of March ( if memory serves), so a truck build date of may should be safe. On a seasoned block, if it hasn't cracked yet, it's probably not going to, so if you don't see any "steamed clean" areas, next to the lifters, (F & R), it may be worth chancing it.