Shift on the fly?

[oldsub86]

When did it become possible to shift into 4Hi while moving? What year truck?

[ryanroo]

i think any truck 3/4 and lower GVW truck with a 208 can do this, so after 1980. you can shift a gear drive (np205) as well if your front hubs are locked in you shouldn't have a problem.
Ryan

[1969 GMC]

its been possible for a while...in my '69 TSM, it says you can shift into and out of 4hi while moving slowly (and this is with the Rockwell T221). i know in the '80s, the NP205 got a syncro low range so you could shift into 4 Lo at slow speeds, also.

[oldsub86]

I test drove a 1984 GMC K1500 that I was interested in on Saturday and the fellow who owned it warned me not to try shifting while moving because it would grind. I am used to my 1995 Toyota 4Runner. I can shift in and out of 4 wheel drive at speed and do depending on the road conditions. I have to stop to put it into 4L but 4H is not problem. I was a bit surprised that the GM was like that. Is this normal or did it have a problem? The truck was not original. He said it has had a replacement 350 engine and transmission. It would have originally had a 700R4 I suspect given that the shifter indicator in the dash showed an overdrive position but the tranny was only a 3 speed and he warned me that I had to put it in the OD position because if I put it in the D position I would be locked in 2nd gear.
I didn't buy the truck because he wanted a lot for it and it needed a lot. The body was nice but the interior was junk and the running gear was a bit questionable. I'd have cheerfully bought it at a lower price but didn't want to insult him so just passed on it. I really want a 4 wheel drive pickup but I don't really want another project. Given the body I hoped the rest of the truck would match. Then a bigger price would be acceptable.

[STEVE A WILBURN]

I Have A 1988 And It Was The First Year I Remember

[DirtyLarry]

I have pretty much owned them all at one point or another and you can shift almost any transfercase into 4 Hi on the fly. Easy off the throttle and pull the lever into 4 Hi. I can even poke my NP205 into 4 low while in motion…..very slow motion but it will go.

The reason 1988 sticks in everybodies mind is because that we the year the GMT400 trucks were introduced and “Shift on the fly” actually became a marketing line.