Looking to swap a 1979 Bonanza to an Automatic Overdrive

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

midgetorama

Junior Member
Joined
Oct 28, 2024
Posts
3
Reaction score
1
Location
Montana
First Name
Casey
Truck Year
1979
Truck Model
Bonanza
Engine Size
350
My dad has an ultra clean 1979 Bonanza. Now that he's retired he's driving it more and hates the 4.10 gears at highway speeds. I believe it has the NP203 in it since it's full time 4WD and it's paired to a TH400 and 350 ci.

Can anyone recommend the most straightforward swap to an OD trans? I'm not opposed to a new transfer case swap with lockout hubs.

Happy to provide more information on the pickup to help with recommendations. Thanks!
 

ali_c20

Full Access Member
Joined
Sep 20, 2016
Posts
1,252
Reaction score
1,789
Location
Austria
First Name
Alexander
Truck Year
1974, 1979
Truck Model
C20, K5
Engine Size
350, 350
Welcome from Austria. When I read the title I wanted to answer: Ask NickTransmission.... but I was too late :)
 

NickTransmissions

Supporting Member
Supporting Member
Joined
Aug 3, 2023
Posts
399
Reaction score
825
Location
Las Vegas
First Name
Nick
Truck Year
1987
Truck Model
R10
Engine Size
350
Thank you. It appears a 700 can be mated to a 203, though not optimal. Is there a recommended transfer case for this swap also? Thanks again!
You're welcome...I'm not sure on the t-case as that would depend on whether you had a driver side or pass side drop for the front diff but a nicely built 700R4, assuming your engine won't be making more than about 500 HP and/or full race, will make for a great cruiser on the hwy while still giving you decent city mileage (i.e you wont give anything up vs a TH350 or TH400).
 

legopnuematic

Licensed Junk Dealer
Supporting Member
Joined
Oct 27, 2016
Posts
2,406
Reaction score
6,055
Location
MO
First Name
Spencer
Truck Year
1971, 1̶9̶7̶4, 1976, 1979,1̶9̶8̶5, 2002
Truck Model
Dart Swinger, Sierra 10, C10 Cheyenne, C10 Big Ten, Silverado 10, Ram 2500
Engine Size
225/6, 350 c.i., 350 c.i., 5.9l Cummins
If you go with a 700r4, an NP208 would probably be the easiest solution as they are rather plentiful and came behind 700r4s from the factory.

They are plenty strong.

If you do go to a part time case, don’t forget to get some manual locking hubs.
 

midgetorama

Junior Member
Joined
Oct 28, 2024
Posts
3
Reaction score
1
Location
Montana
First Name
Casey
Truck Year
1979
Truck Model
Bonanza
Engine Size
350
It's a passenger side differential and I doubt the pickup will ever have more than 400 hp even the motor is rebuilt or swapped. I guess the search begins for a 700 core and 208 transfer case.

Thanks again for the info!
 

Latest posts

Forum statistics

Threads
43,926
Posts
945,843
Members
35,967
Latest member
turnleft2goright
Top