Change 4-Speed to 5-Speed

[halbert09]

I have a 1973 C30 2WD with a 350 V8 and the 4-speed manual trans with granny low.
I would like to replace it with a 5-speed that is overdrive in 5th and still has the granny low 1st gear.
Is there a 5-speed from a later model that would more or less bolt up?
If so, what trans should I look for and what years of GM/Chevy (or other make) might it be from?
What kind of trouble will I possibly encounter, bellhousing? input shaft? drive shaft? cross member mounting, etc?

I think if I can do this it will help a lot on the highway with the 4.11 rear, but of course cost and complications are always a concern.

Thanks for any info.

Harold

[zieg85]

My $.02 is...The NV4500 is pretty much the best way to go from what I have heard.  Cost is a big factor.  What kind of towing do you do?  How is the engine in your truck?  What gas mileage do you get now?  Your final drive will be 3.00 which may not work well with a worn out 350.  I have a 3.21 gear in my 85 and I have not had a problem getting 7K lbs rolling but I have a 454.  Lots of things to think about and return on investment is one I would think.  You can do a rear end gear change to a 3.42 for probably 20% of the cost of a 5 speed.  I am sure others will chime in.  I guess it all depends on how deep your pockets are.  Here is some good reading  http://www.high-impact.net/nv4500.htm 

[halbert09]

My $.02 is...The NV4500 is pretty much the best way to go from what I have heard.  Cost is a big factor.  What kind of towing do you do?  How is the engine in your truck?  What gas mileage do you get now?  Your final drive will be 3.00 which may not work well with a worn out 350.  I have a 3.21 gear in my 85 and I have not had a problem getting 7K lbs rolling but I have a 454.  Lots of things to think about and return on investment is one I would think.  You can do a rear end gear change to a 3.42 for probably 20% of the cost of a 5 speed.  I am sure others will chime in.  I guess it all depends on how deep your pockets are.  Here is some good reading  http://www.high-impact.net/nv4500.htm

Zieg, thanks for the site link.  I had kind of heard thru the grapevine that the NV4500 was the way to go.  Evidentally this trans in GM trucks was used with wide-ratios in 93-94 and closer ratios 95 and up.  High-impact site talks a lot of conversion for Ford and Dodge and transfer case issues but doesn't say much about use in earlier GM 2-wheel drive.  I wonder what exactly would be involved if one could find a trans/bellhousing from a 93-94 GM?  If it would turn out to be just the crossmember, drive shaft mod and maybe bellhousing swap it might be doable reasonable $$, otherwise I will have to forget it.

My 350 is not tired, actually in excellent shape.  Empty it will get 15-17 mpg in a somewhat heavy long wheelbase dually stake body, fully loaded still around 12, all of this if you keep it 55-60mph or less.  I can't see going higher geared than the 4.11 (lower number).  If I got off the road in dirt or starting off with heavy load I don't think the clutch would like it. 

Well we shalll see, maybe a winter project.  Thanks again.

[zieg85]

If you get that kind of mileage you may not gain anything.  That is real good compared to most.  With everything right and keeping my 454 cruising no more than 65 I have gotten as high as 15.7mpg

[pholliday1]

The nv4500 is the tranny of choice. The slave cylinder on your truck is mechanical and the 4500 is hydraulic its some extra fab work but it can be accomplished. It would defiantly be unique good luck keep us posted!

[Edahall]

  If it would turn out to be just the crossmember, drive shaft mod and maybe bellhousing swap it might be doable reasonable $$, otherwise I will have to forget it.

That's about what it takes.  However, this conversion is not cheap and NV4500's have issues with their synchros and 5th gear nut.  If it were me, I would probably buy a rebuilt unit which goes for a little bit over $1k.  Keep in mind, the ratios in a NV4500 are the same as your SM465 except it has a 5th gear.

[bake74]

      There are 2 different ratio versions of the nv4500 .  93 / 94 had a lower 1 st gear.


Current production Dodge NV4500 and GM NV4500 share the same gear ratios. Early GM units (93-94) were built with a lower first gear ratio of 6.34 to 1.0.