NEW YORK (CNN/Money) - After a drop in sales last month, General Motors Wednesday announced increased cash incentives on 2005 model year cars and trucks.

Cash rebates on most 2005 models has been increased by $500 to $1,000, said GM spokeswoman Deborah Silverman. Last month, GM was offering $1,000 rebates on most 2005 models. The range of rebates now runs from $500 to as much as $3,500, Silverman said.

The $3,500 rebates are available only on the Chevrolet Venture and Pontiac Montana minivans, both models that are being discontinued. Most rebates fall into the $500 to $1,500 range, Silverman said.

Rebates are available on vehicles from "traditional" GM brands such as Buick and Chevrolet. No rebates are being offered, however, on Cadillacs.

Additionally, buyers who finance their vehicles through GMAC, General Motors' financing arm, can get an additional $500 to $1,500 rebate. Financing rebates vary by region, model and model year.