Converting old 350 5.7 with a 400 tranny

Asked by Ben Aug 22, 2020 at 03:52 PM about the 1981 GMC Vandura G3500HD Extended

Question type: Shopping & Pricing

I have an old very rare 1980 Vandura 3500 that is a very cool 19' motor home on a 1ton dualy.
Looking for more advice on maybe moving to a LS1 or something better even.  Would be nice to have overdrive on new transmission.
Any information or advice would be appreciated.  
Should have about 12k to kick at it.

3 Answers

Love your rig...mine is a 1982 22ft 405-570-8046..i would also like to know what you did on your ls swap..

Funny, I was just looking up this very same question! I have a 1977 GMC Vandura 3500 Class C motorhome. I currently have a carbureted small block 350, but it struggles up the hills. Looking for something with more power. I was thinking the 6.0 (fuel injected) would fit, but not certain. Any advice would be appreciated!

Been a bit, but have GMC 1980 G3500 Vandura 1-ton DRW. Have a Turbo 400 with Shift Kit & Allison Torque Converter. For power I went from stock 350 small block to a 490 ft/lb 455 hp 383 Stroker Engine. RPM is a bit high over 60 mph on highway, but did get a bit larger profile tires all four, lowered RPM a bit. Also, do not like LS1 or 700 with overdrive, a much weaker transmission. But if affordable, a gear vender will give you six ratios and overdrive. My rear is 4:10 gear ratio, a 3.73 rear gears would be better for you.

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