4 speed vs 5 speed trans

[MTBiker_Boy]

So in my browsing of trying to buy a 620, i see a lot of people advertise a 5 sped transmission swap, but coming to the forums i am having a hard time trying to find any information at all about the differences between transmissions. How much does a 5 speed transmission swap cost, and how is it better than the 4 speed, aside from just having another gear? I think i found one that i like that appears to have a 4 speed, should i use that as a bargaining chip to try to get a better deal?

[datzenmike]

If driving mostly in town a four speed is good enough.

A 5 speed reduces highway RPMs slightly giving a very modest mileage increase and perhaps a quieter ride.

A 5 speed does not allow you to go faster.

A 5 speed is an overdrive for light throttle cruising speeds on the highway and should not be used when passing or climbing hills or if having trouble maintaining speeds on windy days. It should not be used if carrying heavy loads.

 

The '74 and up 620s use a 71B 4 or 5 speed. They are practically identical in every way except for the extra gear. To swap in a 5 speed, just remove the 4 and install the 5 speed. It's as 'drop in' as it gets.

 

As the 4 and 5 speed are actually a six cylinder car transmission used in a truck because of their ruggedness it may not be possible to get one from another truck. If so the transmission you get may have the wrong speedometer drive in it. Just check it is the same color plastic gear or swap your 4 speed one into the 5 speed. The speedometer gear is intimately matched to your truck's rear end gear ratio so keep them together in the ruck..

[MTBiker_Boy]

Ok, that makes sense. I don’t plan on doing a lot of road tripping in it, so i don’t think it should be a problem. If i do find a 5 speed though, what would be a fair price to pay?

[datzenmike]

Hard to evaluate one without driving it in a vehicle first but if in good reasonable running condition say $250-300.