What is the difference between 7700, 7800 and 7710, 7810 John Deere and are they reliable beyond 10,000 hours?
Two different series, so the age to start. Both are quite reliable and basic compared to current machines.
The main difference was the size of the engine. The 77/78 had the 7.6 ltr. Those of 10 had 8.1. They were available with the LH inverter in the steering column as well. The rest was mainly cosmetic.
The biggest difference, as already mentioned, was the engine, the 7000 series had a 6.7 liter engine and the John Deere 7810 series had an 8.1 liter engine. both are good engines, although the power of the 8.1 is higher. The latest 7010 series engines were common rail which are quite reliable so I wouldn’t worry about that.
The front and rear axles / powertrains are pretty much the same. The 7010 series introduced the TLS, and they launched autopower. That is not the ZF transmission, but JD / Funks itself and is generally more reliable. otherwise you have a Powerquad and not the reliability is well known. The cabs are similar but the differences would be the same since the changes are between the 6000 & 6010 series, like the cometic and a few other electronics on the 7010 but not too many.
Personally a JD 7810 50k is IMO one of the best tractors JD has ever made. I would not worry about the hours, if it has been maintained correctly, it can reach 10,000 hours.
There are not many problems with the trans … the trailer disconnect is not good … but unless you plan to stack with it, it will not be a hassle.
Just do a set of pressure tests if in doubt. Less than 3000hrs you will not have any problem, I risk saying. Trailer disconnect problems will sound like a knock under the cab on hard shifting from front to rear.