I’ve been told that the 3 speed will not sell if i ever go to sell it. Is that true?

Mostly true. You may get $20 for it unless you find somebody who trashed their
3 speed and doesn't want to pay $1000+ for a 4 or 5 speed conversion.

What conversion should i do if i do one?

You may as well go all the way and do a 5 speed conversion.

Also right now there is a vibration that grows with rpm’s. I was told that the flywheel is from a 68 bronco and is too big and not balanced. Could this be true?

Small Block Ford engines (260,289,302,351C,351W) came with 2 different flywheels- a 157 tooth and a 164 tooth. A bellhousing originally fitted to a 157T flywheel will not even fit over a 164T flywheel so if you have a larger flywheel you must also have a larger bellhousing. There was no such thing as a 50 oz imbalance flywheel used in a Bronco so if you have a Bronco flywheel it is 28 oz imbalance, the same as your 289 and should not vibrate.

Should i change that (what’s needed bellhousing etc..?) or should i do a tranny swap?

After you buy the car you need to determine exactly which flywheel you have and what's causing the vibration before you do anything else.

 

Thank you so much for addressing my questions

 

The 3 speed was standard and anything else was an option.
The 3 speed is a good strong transmission and will give you no trouble.
as mentioned a 4 or 5 speed will be costly. When i had a 4 speed in mine i would often skip 3rd gear.
if you enjoy driving it let the next guy spend the cash
or put a gearvendors OD on the back of your 3 speed and get a 6 speed.

 

My 3 speed in my 68 has a lower first gear ratio than the 4 speed meaning it would be faster off the line.
Both 3 speed and 4 speed are 1:1 ratio in top gear....so same engine rpm on the highway.
4-speed just has one more shift and one more opportunity to strengthen your left leg.
If you do decide to change it, go to 5 speed.

 

Is this a Mexican car ?

 

🤣

 

I'm in the same boat. An "upgrade" to a 4 speed doesn't seem like much of an upgrade considering all you're doing is shifting one more time to get to the same point, and it costs upwards of 2k to get a trans and do the swap.

I wouldn't pay that kind of money unless it was for a 5 speed.

 

have you looked at the gearvendors OD You get 6 speeds forward 2 reverse and clutchless shifts in and out of OD

 

The 4 speed is ideal however the three speed was the normal issue. Case in point was the thrn new 66 289 my family owned It was a 289 three speed. In 1966 it was accepted that three speeds were not uncommon.

 

Before you go blaming the 3 speed have you ruled out more common issues like a worn out Harmonic Damper/balancer. If yours is original it likely needs replacing. When the rubber dries out and begins to fail you will get vibration that increases with RPM. As the damage progresses it feels like car wants to tear itself apart.

An engine miss, incorrect timing, bad U-Joints, out of balance driveshaft and other issues can also cause the vibration you are feeling. You need to do a bit of diagnoses before dropping a lot of money on a new transmission.

 

I keep a 3 speed around as a backup just in case i break the t5 i can be up and running again in a couple of hours.

 

I've always heard of GV overdrives but I have never directly known anyone that had one. Seems to me that it would only be good in an application with no other options, and only used on the highway for real OD purposes.

 

This is correct and that is why most find there way into RV's. They are also decent for high HP vehicles as they can supposedly handle 1200hp or more. Lots of drag week racers are known to use them when driving the actual race car from track to track.

 

I still row a 3spd in my '66 because I've yet to install the T10 4spd I've had for years. When I finally do the change over, I'll keep the 3spd as a back up. Heck, I've moved the 4spd into two different houses over the years. What's another transmission hanging around. I also have a homeless '67 289 that it could mate to. And I keep looking over at the parts '70s Datsun Z-car my neighbor has next to his garage...

 

 

Exactly. 3 speeds are underrated. 😎

 

My dad tried to get me to pull out the 3 speed and put in a 5 speed. I wanted to keep it original. He said to just put the 3-speed knob on the shifter and no one else would know. (They also might have trouble driving it)

 

You know where the gears are. Who else would drive it? I never look at the pattern on the ball.
would not do me any good as I have a 4 speed ball on a Hurst handle on a T5Z
theft deterrent as well as the 3rd pedal

 

My '65 2+2 was a 289V 3 speed back in the day. I got lots of tickets that totaled 18 points on my driver's record. So, it works just fine LOL! Oh, maybe the COBRA kit w/duals helped?

 

would that be similar to this