LaSalle 3 Speed in a Truck?

[39Flathead]

First of all I fully recognize that this is not the right forum for this question. I know this group is more dedicated to authentic restorations of classic Cadillacs and this is not that. With that being said I'm hoping someone with the technical knowledge could help me out.

Several years ago I bought and restored a "1939" Military 346, at the time for a custom speedster build I was working on. When I say custom I mean a ground up fresh design, it shares no parts with any Cadillac. Struggled with transmission issues until I found an unknown year LaSalle 3 speed side shifter, and after some additional time I found the correct bellhousing from a user on here. Finally I have a complete end to end 346 with trans.

Since then I've moved across the country and lost my garage in the process so I scrapped the speedster build and figured I'd get around to it one day. Fast forward to today and I've picked up a 1942 Chevy g506 military 1.5t truck with no engine or transmission. I absolutely wanted to get this 346 into the Chevy and use it as my weekend toy, occasional home depot truck, light duty offroader (dirt, not rock crawling). Definitely a cushy retired truck life, I have 2019 half ton truck for actual towing. In reality the '42 will have the dogs in the flatbed and cruising around town on sunny days.

I planned on trying to mate my Ford T8 non-synchro 4 speed to the 346 but after completing all my measurements I just don't think it's a realistic plan. After extensive googling I've gained a full understanding of the reported strength of the LaSalle 3 speed. Comparing ratios I know I'm losing the granny low but aside from that the ratios are in the same ballpark: 1/2/3 is generally equivalent to 2/3/4 on the Ford trans.

Considering the truck is about 1.5T heavier than the Cadillac Series 62, and given the reputation of strength and relaxed duty it'll face, would I be crazy to consider using the LaSalle 3 speed in the truck? I figure if people were using it being blown drag motors in the 50's and 60's and I'm using it with a stock 346 in a truck I believe it would be fine....but I also have no hands on experience with it while I'm sure most of you do.

Thoughts on this crazy, non-traditional build that still keeps classic Cadillac parts on the road?

[Brad Ipsen CLC #737]

This transmission was used until 1953 in Cadillac's and later in Oldsmobile OHV V-8's.  Also used in the late V-16's with no modifications.  Ratios are 1:53 to 1 in second and 2.39 to 1 in first.  They do have some wear points so you would want one in good condition.   

[39Flathead]

This transmission was used until 1953 in Cadillac's and later in Oldsmobile OHV V-8's.  Also used in the late V-16's with no modifications.  Ratios are 1:53 to 1 in second and 2.39 to 1 in first.  They do have some wear points so you would want one in good condition.

Ya I'm already familiar with the transmission....not sure if there's a miscommunication on what I'm asking..

[wheikkila]

I think it would be a good transmission for the truck. The only problem I see is getting everything together and not have it jump out of third gear. They use the floating bearing retainer on the front and the clearance is critical. I'm currently working on mine after rebuilding it. I'm rechecking everything. Good luck and I how it works out. Let us know.
            Thanks Wayne 

[39Flathead]

I think it would be a good transmission for the truck. The only problem I see is getting everything together and not have it jump out of third gear. They use the floating bearing retainer on the front and the clearance is critical. I'm currently working on mine after rebuilding it. I'm rechecking everything. Good luck and I how it works out. Let us know.
            Thanks Wayne

Thanks for the input. I rebuilt the 3 speed last year but I'm sure taking it apart for a final check wouldn't hurt!

Ideally I would find a LaSalle with the short shaft from an Olds....but I think that's unrealistic. I contemplated 3D printing a new tail shaft housing and having a shorter output shaft machined but that's just time I don't have right now.

[Jay Friedman]

Tom King in Lambertsville N. Jersey is the guru of these transmissions.  You can't post email addresses on this website, so I'll write it out below with "at" substituting between the number "7" and "aol" to see if that works.  He could probably answer your questions and maybe provide a way to get a 1950 Oldsmobile shorter tail shaft and rear housing. 

thekingco1947ataol.com

["Cadillac Kid" Greg Surfas 15364]

You might consider me a pessimist, but don't you think this trans is a bit light for an 8000# truck?
Greg Surfas

[39Flathead]

Tom King in Lambertsville N. Jersey is the guru of these transmissions.  You can't post email addresses on this website, so I'll write it out below with "at" substituting between the number "7" and "aol" to see if that works.  He could probably answer your questions and maybe provide a way to get a 1950 Oldsmobile shorter tail shaft and rear housing. 

thekingco1947ataol.com

Emailed, thanks!

[Poncholover]

Fascinating project, the LaSalle trans has a pretty high first gear though. That should rule out hole shots!

[harry s]

Given the intended use I would say the trans would hold up. I'm sure the axle ratio is way up there. I know one thing it will be the best sounding WW II truck around. Will you have 4X4 or just RWD? Harry

[Tom Beaver]

I do have an Olds tail shaft housing that has never been used.  I do not have and Olds tail shaft however.  I you could use the tail shaft housing let me know.

Tom Beaver

[39Flathead]

Given the intended use I would say the trans would hold up. I'm sure the axle ratio is way up there. I know one thing it will be the best sounding WW II truck around. Will you have 4X4 or just RWD? Harry

4x4, to use the LaSalle I'll have to shift the transfer case back about a foot to leave room for a very short shaft to the divorced case.

I was curious if the LaSalle would hold up to the weight of the truck but given the use I'm hoping it will be ok. I'm contemplating adapting something like a BW T98 to it but it gets a bit complex.

[toybox]

  Having seen one used behind a 413 duel quad mopar on the dragstrip in a 34 ford coup for years I would say yes it will hold up. Tim

[39Flathead]

Fascinating project, the LaSalle trans has a pretty high first gear though. That should rule out hole shots!

Haha based on my math in first gear with the LaSalle I should see 7.5 mph @ 1k rpm, 15 mph @2k rpm, 22 mph @ 3k rpm.

Seems like a reasonable curve if I assume this motor will want to be shifted around 2k rpm.