Hola Folks

[cdvntx 3]

My name is Chris and I reside in the great state of Texas. In the DFW area to be a little more precise. I'm about to pull the trigger on a 1962 B-61 END673P. I'm not sure what the "P" designates as this is my maiden voyage into the vintage Mack truck world. So, I'll be seeking lots of help from the elders, lol. More about the truck. It has the Triplex transmission. Single rear axle. It's geared pretty low and I'd like to explore making it more highway friendly.

[yarnall 965]

Welcome to the forum Chris.  That's a pretty neat truck with the winch and track. I hope the purchase works out. I'm in PA but my brother lives in Lufkin.  Mike.  

[Freightrain 2,506]

The "P" Motor is a good, non turbo motor.  It has the split intake manifold.  Same motor that was in my truck until I upgraded a few years ago.

Take a look at the rear end, on the drivers side of the gearset, will be a flat spot with a part number and gear ratio(like 4.62, or whatever).  The same goes for the transmission.  It will tell you if it is a single OD or Double OD version:  like TRT-722 or TRT 7220.   You can look at the transmission shift tag on the roof, but they are not always accurate to what is still in the truck.

Truck looks pretty solid.  Hope you get it.

[j hancock 13,665]

Truck looks good!  Hopefully you can do a deal.

[HarryS 454]

Nice looking B. It will be interesting to see what the gearing is which can always be changed to suit.

[cdvntx 3]

On 5/24/2018 at 9:34 AM, HarryS said:

Nice looking B. It will be interesting to see what the gearing is which can always be changed to suit.

Owner says 60-65 mph. I'll be looking for taller gears

[cdvntx 3]

On 5/23/2018 at 10:11 PM, Freightrain said:

The "P" Motor is a good, non turbo motor.  It has the split intake manifold.  Same motor that was in my truck until I upgraded a few years ago.

Take a look at the rear end, on the drivers side of the gearset, will be a flat spot with a part number and gear ratio(like 4.62, or whatever).  The same goes for the transmission.  It will tell you if it is a single OD or Double OD version:  like TRT-722 or TRT 7220.   You can look at the transmission shift tag on the roof, but they are not always accurate to what is still in the truck.

Truck looks pretty solid.  Hope you get it.

It has the 15 spd triplex. I think I went thru 6 gears before getting out of the driveway, lol.

[Freightrain 2,506]

Sounds like it's geared just like mine was 4.62 gears.  With single OD it would run 65 mph flat out.   Did that for years pulling my trailer, just holding it to the floor and go!

With 4.10 gears it is 72 mph.  They made 4.00 for these trucks but finding that ratio will be likely hard to do.   I replaced mine with air ride Rockwell and found the 4.10 gears for it.

[Maddog13407 2,193]

got a 4.00 in mine out of a U model with a 711 and triplex and its fun to drive but put some weight on her and your shifting your ass off

[cdvntx 3]

22 hours ago, Freightrain said:

Sounds like it's geared just like mine was 4.62 gears.  With single OD it would run 65 mph flat out.   Did that for years pulling my trailer, just holding it to the floor and go!

With 4.10 gears it is 72 mph.  They made 4.00 for these trucks but finding that ratio will be likely hard to do.   I replaced mine with air ride Rockwell and found the 4.10 gears for it.

I'll trade you! Yeah, I GPS it @ 65 on level ground. I wouldn't want to do much faster. I was in hilly country and hit 73 downhill with a tailwind, ha! Anyways, lots sorting to do before license and inspection

[cdvntx 3]

I understand Hi/Lo. But Direct has me a little buffaloed. Final gear is Hi/5?

[terry 526]

Looks like an overdrive on the main box, go from 4th hi-split right to 5th high-split. No splitting 5th gear, the rear box is an overdrive too.    terry    If the diagram matchs your gearbox,  Trans model no. should be on the left side of main box.

Edited May 28, 2018 by terry

[Freightrain 2,506]

Yup, looks like you have a DOUBLE OD triplex.  That is a 13 spd Triplex, so you don't split 5th gear.  That is kinda a "get home gear".  Basically don't really use it unless you are empty and wanna run.  It won't pull it very well if you are heavy and on anything but level ground.

[68-f-model 268]

Excellent looking  b-model. The purpose built bumper and rear racks just add to the brute aspect.

Still  jealous of all you guys that fit in a B-model cab.

[BillyT 553]

Terry and  Freightrain, I drove a B model with a 711 and a 13 speed triplex,it was converted from a single axle road tractor to a dump with a rear tag.You split into 4th and went from 4th hi straight to 5th hi, no split therefore considered a 13 not a 15. Would do 80 or at least that's what the Speedo read!