Actually I think if you dig into the specs, it states that the loader is spec'd with the standard 6' bucket attached.
I'm sure of it now... I looked myself.
ML120/ML130 Loader Manual
***QUOTE From page 14: Specifications taken with Mounting Kit, Hose Kit, and (72" Skid Steer Bucket ML120, 75 Skid Steer Bucket ML130.)
Specifications based on ASAE standards S301.3 and furnished for general information only as they can vary with different tractor
models. Specifications are subject to change without notice and without liability therefore.
Lift Capacity to Maximum Height at Pivot Pin 2425# ML120
Keep in mind when calculating things, only a certain percentage of the bucket sets forward of the pins when rolled back, and the entire bucket weight is forward of the pins when rolled down. This variance doesn't exist with all implements you can put on the front. For instance; SSQA pallet forks. Even when rolled back fully, the biggest part of their weight is still forward of the pins. There are no calculations you can really do to tell how much a given implement will increase or decrease the lift capacity without taking the geometric measurements of each and their relation to the to the pins and doing a lot of math. Even then variables such as uneven ground are going to throw the math off. It isn't an exact science.