Need help reguarding my stock antenna wire..., I'm replacing my antenna w/ an aftermarket one... Options

[tin_foil]

Alright, i need some help from someone whos replaced their antenna. I just picked one up at a junkyard off a Celica. It's one of those genaric 12" (+ or -) black rubber ones. Anyway, its got about a 3 foot long cord, that seems to need to be pluged into something like an adaptor at the end of it. When I took it off the junkyard Celi, it just plugged into the stock antenna cord someone around under the back seat. But on my celica, theres no plug... or if there is, I'm not finding it. So am I just missing it? Or am I going to have to splice the two antenna wires together? If that's what I have to do, this that going to make me get worse reception?