If it's a solid red than I would say Laser Red. If it has the slightest tint of orange to it, it's Rio Red. Click on my sig below to see my Rio Red 98.
1998 Mustang Exterior Colors Color Code
Chrome Yellow BZ
Rio Red E8
Laser Red E9
Performance Red ES
Dark Green Satin FU
Atlantic Blue K6
Bright Atlantic Blue K7
Silver YN
Black UA
Autumn Orange BG
Pacific Green PS
Crystal White ZR
I don't kmow where information above came from, but Performance Red ES was not availble in 1998. Here is a breakdown of colors from Yellowmustangregistry.com
1998 Mustangs BY COLOR
Color Name Paint Code Units Sold
Black UA 32,326
Laser Red E9 28,174
Crystal White ZR 26,114
Dark Green Satin FU 17,060
Rio Red E8 16.971
Silver YN 14,560
Atlantic Blue K6 12,151
Pacific Green PS 9,929
Bright Atlantic Blue K7 7,074
Chrome Yellow BZ 6,283
No... see my sig. I have Rio Red. I just think Rio Red is slightly orange and performance red really has some orange in it. I don't think Laser Red has any orange in it. That's all.