Great find, and it looks to be in exceptional shape. I know with these 74-D DDOs, if the grade deviates too far off AU, they're not too valuable. But you have a goodie!
That is a good example of FS-101 DDO. I am always looking for these when I go through rolls of halves. Nice find!
Slabbing is entirely up to you. I like my coins raw, because personally, my varieties are too minor to be slabbed, and I would be losing money on slab fees. If you do intend to slab, you should probably send it to ANACS...they slab pretty much most varieties.
Congrats on a sweet find! I absolutely love that particular DDO and by all means, do not limit your viewing and appreciation of the coin to just the word TRUST as the coin has dramatic doubling on all the letters and date. A well struck example is quite impressive. Unfortunately, the resale market in these is somewhat limited in grades MS64 and below. I've seen XF Examples go for only a dollar or two as the coins themselves are easily located with just a little effort. I remember about 6 years back, buying up every 1974 Mint Set I could get my hands on in order to find one of these. I found one after about 50 0r 60 sets. It graded MS63. In Feb 2008, I found a mint set with one of these in it at the Long Beach Coin Show which graded out at MS64. I've only found one in roll searching but it's ALWAYS a delightful surprise! What I'd recommend is examine the coin closely and then consider searching Mint Sets until you find one that grades at least MS64. You'll be glad you did. MS65 specimens generally sell at around the $200 mark. A word of caution though, these Kennedy DDO and DDR coins can be quite addicting. Again Congrats!