1989 Thunderbird V6 was able without A/C. Through your local dealer, or any Ford / Motorcraft parts distributor, you should still be able to order the idler pulley / bracket assy. that was bolted in place of the A/C compressor on those cars. Don't remember the number for sure off the top of my head, I'm going to guess at E9SZ 8678 A, maybe B. I can check it out tomorrow at work if you like.
i just did the smog and ac delete if you would like i could post the belt size i used cost like $22 at bumper to bumper.
93 LX: 89 SC rear sway, Tokico drop kit, JBA headers,ported and polished Edle Brock intake,ported e7's, E303 cam, Cold air intake,75mm TB,03 Lmaf, TwEECed T4M0, smog pump & ac delete, under drive pulleys, msd 6a, 1.7 ratio roller rockers, electric fan, 3.27 trac lok, 5spd, aluminum drive shaft, digital cluster converted to analog and it works!
The A/C delete pulley and bracket is E9SZ 8678 C, Motorcraft YS-174. Wholesale price is $70.26 up here in Canada, so maybe ~$50 in the U.S. This would go in place of the compressor, and keep the original belt.