Jag - There is another factor in figuring out hp for each model - especially in the L's. Some model numbers correspond to Gross HP, some to PTO HP and some to Net HP.
A reason behind the confusion may be that in the early '80s Kubota's model numbers corresponded roughly to Gross HP, which included everything the engine was doing, including heat and noise.
The L345, for instance had 34.5 gross, and 28 PTO hp, roughly 20% less. But they took some heat from tractor purists who were more interested in ratings based on power available at the PTO - a more honest estimate of what work a tractor could be expected to do besides move itself around.
So in the mid '80s Kubota brought out some L-xx50 tractors where the model number was tied to PTO hp. The L-3750 had 37.5 hp at the shaft, etc.
This means that there are some older L-series tractors with lower numbers which have more power and weight than some newer ones with higher numbers.
Around the early '90s the new models started being named with digits midway between gross and pto - called the "net" hp. I think this continues through L's and M's today.
Hope this is relevant to your question.