The Stovebolt Site Forums The Parking Lot Big Bolts Transmission Swap

 I have a 69 C60 with a 427 and a 5756B 5 speed direct. I had the dual disc clutch rebuilt and it has roughly 20 miles on it now. I have an opportunity to buy another transmission that has OD. I would be able to cruise at 65mph at 3200 rpm without changing anything else.

Is this a direct replacement for my current 5756B? I'm assuming the bellhousing are the same but I have no knowledge of bellhousing numbers. Also would my clutch work with this transmission? I have a lot into the rebuild and would hate to throw that away-so to speak.

This is what the seller sent me.
Seller- I have a spicer 3053A transmission in excellent condition, no odd noises. SAE bellhousing #3 pattern. Manufactured by TMG in England, it's a licensed copy of a Spicer 3053A. Comes with a hydraulic master and slave cylinder and shifter arm.

I don't know that transmission but you would do well to find the ratios for all 5 gears. Unless you already have a 2-speed axle there may be some uncomfortably wide jumps between gears, often between 2nd and third, fourth being direct. Somebody who's more familiar with Spicers will know. What I know is that the first digit in the model number usually indicates the torque rating. So you would find an 8000 series behind a big 855 Cummins like a 335 or 350 and a 6 series behind a 4-71 or maybe 6-71 Detroit. I have seen the 5 series in dump trucks powered by a 534 gasser and backed by a, say, 5831A Spicer brownie.

Google 3053A to get ratios. I think it is a pretty wide ratio trans, OD is not very high, someone make higher ratio gears for it. Takes a normal bell housing but has 5th hole.

I agree with Tommy, many trans’ that are just made from a direct 5 speed, unless one has a 2 speed rear, the jump from 2nd to 3rd is too big.

Ed

I do have a 2 speed rear and currently have 6:50 high 8.87 low ratio rear. I need more top end speed and currently take off in 2H empty and I can push it to 65 but she's really screaming at those rpms.

I would not hesitate to swap them if it's a bolt in swap. The 427 should have no problem pulling a wide ratio. Way back when I worked for a beer distributor we had lots of 366 and 427 engines with 4 speed/2 speed drive trains, had no issues with being able to to pull the loads. Tractors were plated at 28,000 - 38,000 lbs. depending on what wagon they were assigned to. I'd go for it.

The Spicer 5756B 5-speed is listed as a "close-ratio" and was only available when the 2-speed rear and 427 engine were ordered. It's ratios are as folllows;

1st = 6.50
2nd = 3.52
3rd = 1.93
4th = 1.18
5th = Direct
Reverse = 6.88

Here's the ratios for the Spicer 3053A

1st = 6.00
2nd = 3.31
3rd = 1.89
4th = Direct
5th = 0.85
Reverse = 5.90

Mike B

Thank you for all the info guys! Does anyone know if it is a direct swap? If it is I'll pull the trigger and go for it.

I wrote a side by side comparison based off of the numbers Mike B gave and the difference between 1 low through 3 high are so small in both high and low range the difference is less than 1 mph per gear shift. From 4 low up there is quite a difference assuming I shift at 3200 rpm in all scenarios (on paper). The power the 427 has as 78buckshot said is quite high. I don't see me having a problem. If I do i can just put the 5756B back into it. I also have a set of 5:29 gears sitting in my garage as an option too. A transmission change is faster than a hear swap.

Does anyone know what clutch the 3053A uses? Is there a spline size/count difference between the two transmissions? Are both bell housings the same enough to swap?

Edit: I have found for the specs for the 3053A input shaft. It is 10 spline 1-1/2". I am unable to locate the spline and size of my 5756B as of now.

Sounds like it's time to get the tape measure out and see what's in your truck or find someone with a 5756B that's sitting on the floor...

You need to confirm the Pilot bearing size, shaft size, spline count, length of the input shaft and trans to bell housing bolt pattern. I don't see the 3053A as ever being in a GM truck from the factory, so my parts books are no help.

The Medium Duty trucks could have a 11", 12" or 13" clutch.

Does your 427 have a SAE transmission adaptor ring for a SAE bellhousing or does it have a GM bellhousing?

Mike B

I really wish I wouldn't have sold my other 5756B, I had one sitting around for quite awhile.

These are all hard things for me to confirm from either end, though I do know that mine is a 10 spline input shaft. It's too cold for me to pull my trans and have a look and the seller "is out of town". I may have pictures from the multiple times I've had to pull my trans. I'll look around in the garage, I hope I still have the alignment pin for my clutch. I know that I have a dual disc clutch and can probably find the specs for that online, they were not very common from what I've read. Detroit Clutch Masters told me it was one of the first dual disc clutches when they rebuilt it.

I do have an adapter on the back of the motor/front of the trans. It's about 4-5" thick or so and my starter bolts to it.

I'm in the midst of trying to wrap up a lot of things on my old Willys truck I've been building since that fits in my garage. If I do pull the trigger on this trans it will sit until it's warm enough out to do a swap.

Here is a link to a place selling the 3053A that I came across while looking https://www.boyceequipment.com/transmissions . It states
*The 3053A Spicer Transmission fit almost all Diesel applications as well as most Chevrolet engines.  Dodge and Ford applications are more expensive to install.*

Considering the price the seller is asking I maybe willing to take the gamble.

Have you looked into the Spicer 6853C transmissions that came in Chevrolet/GMC diesel trucks? I believe they are a direct bolt in replacement for your 5756B...they may even share the same case and could be half the cost of the 3053A.

Spicer 6853C...

1 = 5.71
2 = 3.00
3 = 1.78
4 = Direct
5 = 0.85
R = 5.73

Mike B

Thanks Mike! I'm going to move forward and purchase the 3053A. Worse case scenario I can't use it and I install my 5:29 gears then sell the trans.

The deal fell apart on me getting the 3053A so I'm back to the drawing board.

Have you thought about a TH400 behind your BBC with a Gear Vendor OD unit? That might be cheaper than buying a BIG truck trans with OD built in...Lots of motor homes run this set-up!

Around hear you can get old falling apart motor homes for free because NO junk yard will take them. I passed on a free coach that had a low mileage 454 with TH400 because I couldn't get rid of the spoils after I took what I wanted. My next door neighbor also had a mini excavator and dumpster show up to break their 36' MH up and haul it away...it had been covered with a tarp for years and the inside was covered in mold...I didn't know about this until it was to late, but I'm sure I could have asked for the drive train after they pulled the body off if I had had advanced notice...

Mike B

With my work schedule I'm trying to stay away from anymore custom work than I have to do. I'd rather spend more money and not take as much time to make a change to the C60. If I can come across an OD trans I'll jump on it otherwise I'll either put in the 5:29 gear set I have or find a whole other 3rd member for a quick change out. I'm in the midst of trying to wrap up my 52 Willys pickup, it's a bit of a rat rod with fine tuning done here and there and that takes up most of the very limited time I have.