HP req for new idea/Agco/MF disc mowers

Hi all

I have a early '90s 3 point New Idea 5409 mower and would like to replace it.  I'm considering a New Idea 5209 pull type with conditioner.  It seems this is a very similar cutter bar to the 5409.  correct?

 

I use a JD 2640 (70 HP) and can mow my 20 ac level fields, 2/3 ton ac grass, at about 4/5 mph and I'm satisfied with this speed.

 

Do I have enough tractor to switch to a pull type like 5209?  I understand newer models have dipsticks to eliminate the need to remove the gearbox cover to check grease levels?  There are not any of these in area to go look at easily. I'm just shopping on the internet.  What year or serial number did that begin?

 

Any thoughts on which ones to look for ?

 

Thanks in advance

HP req for new idea/Agco/MF disc mowers