I'd certainly check the vac modulator in that case. It may have even just come unplugged at the transmission end. That can happen as the rubber get's old and swells if it's got fluids on it and it gets spongy and rots, or even gets brittle and cracks and then leaks air sucking air instead of letting the modulator feell the full vacuum. So yes, by all means, check the vac hose at both ends. If those are good, then swap another known good modulator on it. Keep in mind, some look different than that biggo canister type. Most people now have the little brass bell looking type and they work just as well and maybe even better since they're adustable with a tiny screw inside the vac hole. You can turn it in a tighten up the spring that the vac needs to overcome to move the modulator valve and delay the shift points, or back it out to make them earlier shift points.