What opportunities do I have in the Army at 42 years old, prior service?

The best answer I can give you is your chances of getting into RA is rather low. I would check the mos availability list to see whats low and needs more people. I know they were taking anyone they could get that met certain experience criteria for the last IT position that opened up. Honestly its reliant on whats in demand and if you can present yourself as competetive. I would check the reserves and national guard as I know they have a harder time recruiting and maintaining numbers and a lower competition rate for starting positions. although the promotion rates are super slow and sometimes impossible up to a certain point.

Best bet is go talk to a recruiter
It’s the Army, they’ll probably get you an age waiver.

I was Innactive Reserve for 13 years. I did have prior service 15 in what I considered a dead, never gonna get promoted above E6 MOS. So I went Innactive. I was in a rut, overweight, and needing a job so I went TPU. One year later I got orders for Iraq. I was 49, turned 50 over there. I came back and stayed with my reserve unit and eventually retired. The opportunities are there you just need to pursue them. Best of luck.

I was prior service Marine with 16 years active duty when I was part of the RIF in Feb 1991. I went back to school received a Degree in Nursing in 1995. In 2003 December 26 at the age of 48 I was able to enlist in the U.S. Army reserves, commissioned a 1LT and assigned to a Combat Support Hospital. In Nov 2006 I received orders for 545 days of active duty, assigned to attend Civil Affairs Course then deployed to Iraq in support of OIF! Deployed at the age of 51 presented quite a challenge but I completed my deployment in March 2008, retired in Dec 2015 with the rank of Captain! So you see age is just a number, good luck and I hope you are able to achieve your goals!

Update: I'm going to try and use my Chemistry degree to get a good job.

60% disability? Could prevent you from re-enlisting, but I’m not qualified to give advice here. If I’m not mistaken, 36 years of age is the cutoff for commissioning and add your 8 years of prior service, you might make the age requirement. I only know this from the experience of a family member. No expert. Best of .luck.

I understand that the NG can be a little more accommodating to retreds in their 40s

It all depends on your disability, your weight, how much more do U need to loose.
I wish U luck in UR efforts.

Depends how good your resume is. Active, Guard, or Reserve? Should look for where they need people the most and where you want to be, line the two up.

A "little" overweight, 60% disabled, and female. Why would the military find this desirable?