I don't have much info about the 1400 series amplifiers, but I did own one and do know they had a 50 watt 2xEL34 power section with huge transformers like the 1200's. VERY loud for 50 watts, lots of punch! The 1400 also had a higher gain Marshall-like sound, with a little Hiwatt thrown in. The pull pot kicked in a lot of gain, good for some headbanging metal. The 1400 did not have reverb. They also were a little less expensive than the 1200's.
1400 Head - MSRP $845 (1990)
1400 Combo 2x10" - $N/A
I see these stupidly cheap, which is surprising. Much better build quality than a new Marshall!